SELECT 
  SQL_CALC_FOUND_ROWS (
    CASE WHEN products.parent_product_id <> 0 THEN products.parent_product_id ELSE products.product_id END
  ) AS product_id, 
  descr1.product as product, 
  companies.company as company_name, 
  COALESCE(
    cscart_master_products_storefront_min_price.price, 
    MIN(
      IF(
        prices.percentage_discount = 0, 
        prices.price, 
        prices.price - (
          prices.price * prices.percentage_discount
        )/ 100
      )
    )
  ) as price, 
  GROUP_CONCAT(
    products.product_id 
    ORDER BY 
      products.parent_product_id ASC, 
      products.product_id ASC
  ) AS product_ids, 
  GROUP_CONCAT(
    products.product_type 
    ORDER BY 
      products.parent_product_id ASC, 
      products.product_id ASC
  ) AS product_types, 
  GROUP_CONCAT(
    products.parent_product_id 
    ORDER BY 
      products.parent_product_id ASC, 
      products.product_id ASC
  ) AS parent_product_ids, 
  products.product_type, 
  products.parent_product_id, 
  products.master_product_offers_count, 
  products.master_product_id, 
  products.company_id, 
  IF(
    products.age_verification = 'Y', 
    'Y', 
    IF(
      cscart_categories.age_verification = 'Y', 
      'Y', cscart_categories.parent_age_verification
    )
  ) as need_age_verification, 
  IF(
    products.age_limit > cscart_categories.age_limit, 
    IF(
      products.age_limit > cscart_categories.parent_age_limit, 
      products.age_limit, cscart_categories.parent_age_limit
    ), 
    IF(
      cscart_categories.age_limit > cscart_categories.parent_age_limit, 
      cscart_categories.age_limit, cscart_categories.parent_age_limit
    )
  ) as age_limit, 
  1 as instock_marker, 
  IF(
    products.product_type = 'C', 
    (
      SELECT 
        MAX(amount) 
      FROM 
        cscart_products 
      WHERE 
        parent_product_id = products.product_id
    ) > 0, 
    IF(
      IF(
        products.tracking = 'O', 
        (
          SELECT 
            MAX(amount) 
          FROM 
            cscart_product_options_inventory s_inventory 
          WHERE 
            s_inventory.product_id = products.product_id
        ) > 0, 
        products.amount > 0
      ), 
      1, 
      IF(products.tracking = 'D', 1, 0)
    )
  ) as instock_sorting 
FROM 
  cscart_products as products 
  LEFT JOIN cscart_product_descriptions as descr1 ON descr1.product_id = products.product_id 
  AND descr1.lang_code = 'en' 
  LEFT JOIN cscart_product_prices as prices ON prices.product_id = products.product_id 
  AND prices.lower_limit = 1 
  LEFT JOIN cscart_companies AS companies ON companies.company_id = products.company_id 
  INNER JOIN cscart_products_categories as products_categories ON products_categories.product_id = products.product_id 
  INNER JOIN cscart_categories ON cscart_categories.category_id = products_categories.category_id 
  AND (
    cscart_categories.usergroup_ids = '' 
    OR FIND_IN_SET(
      0, cscart_categories.usergroup_ids
    ) 
    OR FIND_IN_SET(
      1, cscart_categories.usergroup_ids
    )
  ) 
  AND cscart_categories.status IN ('A', 'H') 
  AND cscart_categories.storefront_id IN (0, 1) 
  LEFT JOIN cscart_warehouses_sum_products_amount as war_sum_amount ON war_sum_amount.product_id = products.product_id 
  LEFT JOIN cscart_master_products_storefront_offers_count AS master_products_storefront_offers_count ON master_products_storefront_offers_count.product_id = products.product_id 
  AND master_products_storefront_offers_count.storefront_id = 1 
  LEFT JOIN cscart_master_products_storefront_min_price ON cscart_master_products_storefront_min_price.product_id = prices.product_id 
  AND cscart_master_products_storefront_min_price.storefront_id = 1 
WHERE 
  1 
  AND cscart_categories.category_id IN (
    2698, 
    2699, 
    2700, 
    2701, 
    2702, 
    2703, 
    2704, 
    2705, 
    2719, 
    2720, 
    2721, 
    2722, 
    2723, 
    2766, 
    2767, 
    2796, 
    2797, 
    2798, 
    2799, 
    2803, 
    2804, 
    2805, 
    2806, 
    2807, 
    2808, 
    2809, 
    2810, 
    2811, 
    2812, 
    2813, 
    2814, 
    2815, 
    2816, 
    2817, 
    2818, 
    2819, 
    2820, 
    2821, 
    2822, 
    2823, 
    2824, 
    2825, 
    2826, 
    2827, 
    2828, 
    2829, 
    2830, 
    2831, 
    2832, 
    2833, 
    2834, 
    2835, 
    2836, 
    2837, 
    2838, 
    2839, 
    2840, 
    2841, 
    2842, 
    2843, 
    2844, 
    2845, 
    2846, 
    2847, 
    2848, 
    2849, 
    2850, 
    2879, 
    2880, 
    2881, 
    2882, 
    2883, 
    2884, 
    2885, 
    2886, 
    2887, 
    2888, 
    2889, 
    2890, 
    2891, 
    2892, 
    2893, 
    2894, 
    2895, 
    2896, 
    2897, 
    2898, 
    2899, 
    2900, 
    2901, 
    2902, 
    2903, 
    2904, 
    2905, 
    2906, 
    2907, 
    2908, 
    2909, 
    2910, 
    2911, 
    2912, 
    2913, 
    2914, 
    2915, 
    2916, 
    2917, 
    2918, 
    2919, 
    2920, 
    2921, 
    2924, 
    2925, 
    2926, 
    2927, 
    2928, 
    2929, 
    2930, 
    2931, 
    2932, 
    2933, 
    2987, 
    2988, 
    2989, 
    2990, 
    2991, 
    3111, 
    3112, 
    3113, 
    3114, 
    3116, 
    3117, 
    3118, 
    3119, 
    3120, 
    3121, 
    3122, 
    3123, 
    3124, 
    3125, 
    3126, 
    3127, 
    3128, 
    3129, 
    3130, 
    3131, 
    3132, 
    3133, 
    3152, 
    3153, 
    3154, 
    3155, 
    3156, 
    3157, 
    3158, 
    3159, 
    3160, 
    3162, 
    3163, 
    3164, 
    3165, 
    3166, 
    3167, 
    3168, 
    3169, 
    3333, 
    3334, 
    3335, 
    3336, 
    3337, 
    3338, 
    3339, 
    3340, 
    3341, 
    3342, 
    3368, 
    3369, 
    3370, 
    3371, 
    3372, 
    3373, 
    3161, 
    2878, 
    2802, 
    2923, 
    3115
  ) 
  AND (
    companies.status IN ('A', 'S') 
    OR products.company_id = 0
  ) 
  AND products.company_id IN (137, 138, 146, 0) 
  AND (
    products.usergroup_ids = '' 
    OR FIND_IN_SET(0, products.usergroup_ids) 
    OR FIND_IN_SET(1, products.usergroup_ids)
  ) 
  AND products.status IN ('A') 
  AND prices.usergroup_id IN (0, 0, 1) 
  AND products.master_product_status IN ('A') 
  AND products.master_product_id = 0 
  AND (
    products.company_id > 0 
    OR (
      master_products_storefront_offers_count.count > 0
    )
  ) 
  AND products.product_type != 'D' 
GROUP BY 
  product_id 
ORDER BY 
  instock_sorting DESC, 
  price asc, 
  products.product_id ASC 
LIMIT 
  0, 20

Query time 0.03294

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "4850.07"
    },
    "ordering_operation": {
      "using_filesort": true,
      "grouping_operation": {
        "using_temporary_table": true,
        "using_filesort": true,
        "buffer_result": {
          "using_temporary_table": true,
          "nested_loop": [
            {
              "table": {
                "table_name": "war_sum_amount",
                "access_type": "system",
                "possible_keys": [
                  "PRIMARY"
                ],
                "rows_examined_per_scan": 0,
                "rows_produced_per_join": 1,
                "filtered": "0.00",
                "const_row_not_found": true,
                "cost_info": {
                  "read_cost": "0.00",
                  "eval_cost": "0.10",
                  "prefix_cost": "0.00",
                  "data_read_per_join": "16"
                },
                "used_columns": [
                  "product_id"
                ]
              }
            },
            {
              "table": {
                "table_name": "master_products_storefront_offers_count",
                "access_type": "system",
                "possible_keys": [
                  "PRIMARY",
                  "idx_storefront_id"
                ],
                "rows_examined_per_scan": 0,
                "rows_produced_per_join": 1,
                "filtered": "0.00",
                "const_row_not_found": true,
                "cost_info": {
                  "read_cost": "0.00",
                  "eval_cost": "0.10",
                  "prefix_cost": "0.00",
                  "data_read_per_join": "16"
                },
                "used_columns": [
                  "storefront_id",
                  "product_id",
                  "count"
                ]
              }
            },
            {
              "table": {
                "table_name": "cscart_master_products_storefront_min_price",
                "access_type": "system",
                "possible_keys": [
                  "PRIMARY"
                ],
                "rows_examined_per_scan": 0,
                "rows_produced_per_join": 1,
                "filtered": "0.00",
                "const_row_not_found": true,
                "cost_info": {
                  "read_cost": "0.00",
                  "eval_cost": "0.10",
                  "prefix_cost": "0.00",
                  "data_read_per_join": "16"
                },
                "used_columns": [
                  "storefront_id",
                  "product_id",
                  "price"
                ]
              }
            },
            {
              "table": {
                "table_name": "cscart_categories",
                "access_type": "range",
                "possible_keys": [
                  "PRIMARY",
                  "c_status",
                  "p_category_id"
                ],
                "key": "PRIMARY",
                "used_key_parts": [
                  "category_id"
                ],
                "key_length": "3",
                "rows_examined_per_scan": 185,
                "rows_produced_per_join": 7,
                "filtered": "4.00",
                "index_condition": "(`s2cart`.`cscart_categories`.`category_id` in (2698,2699,2700,2701,2702,2703,2704,2705,2719,2720,2721,2722,2723,2766,2767,2796,2797,2798,2799,2803,2804,2805,2806,2807,2808,2809,2810,2811,2812,2813,2814,2815,2816,2817,2818,2819,2820,2821,2822,2823,2824,2825,2826,2827,2828,2829,2830,2831,2832,2833,2834,2835,2836,2837,2838,2839,2840,2841,2842,2843,2844,2845,2846,2847,2848,2849,2850,2879,2880,2881,2882,2883,2884,2885,2886,2887,2888,2889,2890,2891,2892,2893,2894,2895,2896,2897,2898,2899,2900,2901,2902,2903,2904,2905,2906,2907,2908,2909,2910,2911,2912,2913,2914,2915,2916,2917,2918,2919,2920,2921,2924,2925,2926,2927,2928,2929,2930,2931,2932,2933,2987,2988,2989,2990,2991,3111,3112,3113,3114,3116,3117,3118,3119,3120,3121,3122,3123,3124,3125,3126,3127,3128,3129,3130,3131,3132,3133,3152,3153,3154,3155,3156,3157,3158,3159,3160,3162,3163,3164,3165,3166,3167,3168,3169,3333,3334,3335,3336,3337,3338,3339,3340,3341,3342,3368,3369,3370,3371,3372,3373,3161,2878,2802,2923,3115))",
                "cost_info": {
                  "read_cost": "128.77",
                  "eval_cost": "0.74",
                  "prefix_cost": "129.51",
                  "data_read_per_join": "26K"
                },
                "used_columns": [
                  "category_id",
                  "usergroup_ids",
                  "status",
                  "age_verification",
                  "age_limit",
                  "parent_age_verification",
                  "parent_age_limit",
                  "storefront_id"
                ],
                "attached_condition": "(((`s2cart`.`cscart_categories`.`usergroup_ids` = '') or (0 <> find_in_set(0,`s2cart`.`cscart_categories`.`usergroup_ids`)) or (0 <> find_in_set(1,`s2cart`.`cscart_categories`.`usergroup_ids`))) and (`s2cart`.`cscart_categories`.`status` in ('A','H')) and (`s2cart`.`cscart_categories`.`storefront_id` in (0,1)))"
              }
            },
            {
              "table": {
                "table_name": "products_categories",
                "access_type": "ref",
                "possible_keys": [
                  "PRIMARY",
                  "pt"
                ],
                "key": "PRIMARY",
                "used_key_parts": [
                  "category_id"
                ],
                "key_length": "3",
                "ref": [
                  "s2cart.cscart_categories.category_id"
                ],
                "rows_examined_per_scan": 2728,
                "rows_produced_per_join": 20187,
                "filtered": "100.00",
                "using_index": true,
                "cost_info": {
                  "read_cost": "127.97",
                  "eval_cost": "2018.72",
                  "prefix_cost": "2276.20",
                  "data_read_per_join": "315K"
                },
                "used_columns": [
                  "product_id",
                  "category_id"
                ]
              }
            },
            {
              "table": {
                "table_name": "products",
                "access_type": "eq_ref",
                "possible_keys": [
                  "PRIMARY",
                  "status",
                  "idx_master_product_id"
                ],
                "key": "PRIMARY",
                "used_key_parts": [
                  "product_id"
                ],
                "key_length": "3",
                "ref": [
                  "s2cart.products_categories.product_id"
                ],
                "rows_examined_per_scan": 1,
                "rows_produced_per_join": 1009,
                "filtered": "5.00",
                "cost_info": {
                  "read_cost": "0.00",
                  "eval_cost": "100.94",
                  "prefix_cost": "4294.92",
                  "data_read_per_join": "7M"
                },
                "used_columns": [
                  "product_id",
                  "product_type",
                  "status",
                  "company_id",
                  "amount",
                  "usergroup_ids",
                  "tracking",
                  "age_verification",
                  "age_limit",
                  "parent_product_id",
                  "master_product_id",
                  "master_product_status",
                  "master_product_offers_count"
                ],
                "attached_condition": "((`s2cart`.`products`.`master_product_id` = 0) and (`s2cart`.`products`.`company_id` in (137,138,146,0)) and ((`s2cart`.`products`.`usergroup_ids` = '') or (0 <> find_in_set(0,`s2cart`.`products`.`usergroup_ids`)) or (0 <> find_in_set(1,`s2cart`.`products`.`usergroup_ids`))) and (`s2cart`.`products`.`status` = 'A') and (`s2cart`.`products`.`master_product_status` = 'A') and ((`s2cart`.`products`.`company_id` > 0) or <cache>((NULL > 0))) and (`s2cart`.`products`.`product_type` <> 'D'))"
              }
            },
            {
              "table": {
                "table_name": "companies",
                "access_type": "eq_ref",
                "possible_keys": [
                  "PRIMARY"
                ],
                "key": "PRIMARY",
                "used_key_parts": [
                  "company_id"
                ],
                "key_length": "4",
                "ref": [
                  "s2cart.products.company_id"
                ],
                "rows_examined_per_scan": 1,
                "rows_produced_per_join": 1009,
                "filtered": "100.00",
                "cost_info": {
                  "read_cost": "0.00",
                  "eval_cost": "100.94",
                  "prefix_cost": "4395.86",
                  "data_read_per_join": "9M"
                },
                "used_columns": [
                  "company_id",
                  "status",
                  "company"
                ],
                "attached_condition": "<if>(found_match(companies), ((`s2cart`.`companies`.`status` in ('A','S')) or (`s2cart`.`products`.`company_id` = 0)), true)"
              }
            },
            {
              "table": {
                "table_name": "descr1",
                "access_type": "eq_ref",
                "possible_keys": [
                  "PRIMARY",
                  "product_id"
                ],
                "key": "PRIMARY",
                "used_key_parts": [
                  "product_id",
                  "lang_code"
                ],
                "key_length": "9",
                "ref": [
                  "s2cart.products_categories.product_id",
                  "const"
                ],
                "rows_examined_per_scan": 1,
                "rows_produced_per_join": 1009,
                "filtered": "100.00",
                "cost_info": {
                  "read_cost": "0.00",
                  "eval_cost": "100.94",
                  "prefix_cost": "4496.80",
                  "data_read_per_join": "7M"
                },
                "used_columns": [
                  "product_id",
                  "lang_code",
                  "product"
                ]
              }
            },
            {
              "table": {
                "table_name": "prices",
                "access_type": "ref",
                "possible_keys": [
                  "usergroup",
                  "product_id",
                  "lower_limit",
                  "usergroup_id"
                ],
                "key": "product_id",
                "used_key_parts": [
                  "product_id"
                ],
                "key_length": "3",
                "ref": [
                  "s2cart.products_categories.product_id"
                ],
                "rows_examined_per_scan": 1,
                "rows_produced_per_join": 1009,
                "filtered": "100.00",
                "cost_info": {
                  "read_cost": "252.34",
                  "eval_cost": "100.93",
                  "prefix_cost": "4850.07",
                  "data_read_per_join": "23K"
                },
                "used_columns": [
                  "product_id",
                  "price",
                  "percentage_discount",
                  "lower_limit",
                  "usergroup_id"
                ],
                "attached_condition": "((`s2cart`.`prices`.`lower_limit` = 1) and (`s2cart`.`prices`.`usergroup_id` in (0,0,1)))"
              }
            }
          ],
          "select_list_subqueries": [
            {
              "dependent": true,
              "cacheable": false,
              "query_block": {
                "select_id": 3,
                "message": "no matching row in const table"
              }
            },
            {
              "dependent": true,
              "cacheable": false,
              "query_block": {
                "select_id": 2,
                "cost_info": {
                  "query_cost": "31651.29"
                },
                "table": {
                  "table_name": "cscart_products",
                  "access_type": "ALL",
                  "possible_keys": [
                    "idx_parent_product_id"
                  ],
                  "rows_examined_per_scan": 270845,
                  "rows_produced_per_join": 27084,
                  "filtered": "10.00",
                  "cost_info": {
                    "read_cost": "4566.79",
                    "eval_cost": "2708.45",
                    "prefix_cost": "31651.29",
                    "data_read_per_join": "203M"
                  },
                  "used_columns": [
                    "amount",
                    "parent_product_id"
                  ],
                  "attached_condition": "(`s2cart`.`cscart_products`.`parent_product_id` = `s2cart`.`products`.`product_id`)"
                }
              }
            }
          ]
        }
      }
    }
  }
}