SELECT 
  cscart_products_categories.product_id, 
  GROUP_CONCAT(
    IF(
      cscart_products_categories.link_type = "M", 
      CONCAT(
        cscart_products_categories.category_id, 
        "M"
      ), 
      cscart_products_categories.category_id
    )
  ) AS category_ids 
FROM 
  cscart_products_categories 
  INNER JOIN cscart_categories ON cscart_categories.category_id = cscart_products_categories.category_id 
  AND cscart_categories.storefront_id IN (0, 1) 
  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') 
WHERE 
  cscart_products_categories.product_id IN (
    275133, 
    275759, 
    275765, 
    276261, 
    276352, 
    276420, 
    276421, 
    276426, 
    276427, 
    276428, 
    276429, 
    276430, 
    276431, 
    276432, 
    276433, 
    276434, 
    276435, 
    276436, 
    276437, 
    276438, 
    276439, 
    276440, 
    276441, 
    276442, 
    276443, 
    276444, 
    276445, 
    276446, 
    276447, 
    276448, 
    276449, 
    276450, 
    276451, 
    276452, 
    276453, 
    276454, 
    276455, 
    276456, 
    276457, 
    276458, 
    276459, 
    276460, 
    276461, 
    276462, 
    276463, 
    276464, 
    276465, 
    276466, 
    276467, 
    276468, 
    276469, 
    276470, 
    276471, 
    276472, 
    276473, 
    276474, 
    276475, 
    276476, 
    276477, 
    276478, 
    276497, 
    276498, 
    276499, 
    276500, 
    276501, 
    276502, 
    276503, 
    276504, 
    276505, 
    276506, 
    276507, 
    276508, 
    276509, 
    276510, 
    276511, 
    276512, 
    276513, 
    276514, 
    276515, 
    276516, 
    276517, 
    276518, 
    276519, 
    276520, 
    276521, 
    276522, 
    276523, 
    276524, 
    276525, 
    276526, 
    276527, 
    276528, 
    276529, 
    276530, 
    276531, 
    276532, 
    276533, 
    276534, 
    276535, 
    276536, 
    276537, 
    276538, 
    276539, 
    276540, 
    276541, 
    276542, 
    276543, 
    276544, 
    276545, 
    276546, 
    276547, 
    276548, 
    276549, 
    276550, 
    276551, 
    276552, 
    276553, 
    276572, 
    276573, 
    276574, 
    276575, 
    276588, 
    276589, 
    276590, 
    276591, 
    276592, 
    276593, 
    276594, 
    276595, 
    276596, 
    276597, 
    276598, 
    276599, 
    276600, 
    276601, 
    276602, 
    276603, 
    276604, 
    276605, 
    276606, 
    276607, 
    276608, 
    276609, 
    276610, 
    276611, 
    276612, 
    276613, 
    276614, 
    276615, 
    276616, 
    276617, 
    276618, 
    276619, 
    276620, 
    276621, 
    276622, 
    276623, 
    276624, 
    276625, 
    276626
  ) 
GROUP BY 
  cscart_products_categories.product_id

Query time 0.00160

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "168.01"
    },
    "grouping_operation": {
      "using_filesort": false,
      "nested_loop": [
        {
          "table": {
            "table_name": "cscart_products_categories",
            "access_type": "range",
            "possible_keys": [
              "PRIMARY",
              "pt"
            ],
            "key": "pt",
            "used_key_parts": [
              "product_id"
            ],
            "key_length": "3",
            "rows_examined_per_scan": 160,
            "rows_produced_per_join": 160,
            "filtered": "100.00",
            "index_condition": "(`s2cart`.`cscart_products_categories`.`product_id` in (275133,275759,275765,276261,276352,276420,276421,276426,276427,276428,276429,276430,276431,276432,276433,276434,276435,276436,276437,276438,276439,276440,276441,276442,276443,276444,276445,276446,276447,276448,276449,276450,276451,276452,276453,276454,276455,276456,276457,276458,276459,276460,276461,276462,276463,276464,276465,276466,276467,276468,276469,276470,276471,276472,276473,276474,276475,276476,276477,276478,276497,276498,276499,276500,276501,276502,276503,276504,276505,276506,276507,276508,276509,276510,276511,276512,276513,276514,276515,276516,276517,276518,276519,276520,276521,276522,276523,276524,276525,276526,276527,276528,276529,276530,276531,276532,276533,276534,276535,276536,276537,276538,276539,276540,276541,276542,276543,276544,276545,276546,276547,276548,276549,276550,276551,276552,276553,276572,276573,276574,276575,276588,276589,276590,276591,276592,276593,276594,276595,276596,276597,276598,276599,276600,276601,276602,276603,276604,276605,276606,276607,276608,276609,276610,276611,276612,276613,276614,276615,276616,276617,276618,276619,276620,276621,276622,276623,276624,276625,276626))",
            "cost_info": {
              "read_cost": "96.01",
              "eval_cost": "16.00",
              "prefix_cost": "112.01",
              "data_read_per_join": "2K"
            },
            "used_columns": [
              "product_id",
              "category_id",
              "link_type"
            ]
          }
        },
        {
          "table": {
            "table_name": "cscart_categories",
            "access_type": "eq_ref",
            "possible_keys": [
              "PRIMARY",
              "c_status",
              "p_category_id"
            ],
            "key": "PRIMARY",
            "used_key_parts": [
              "category_id"
            ],
            "key_length": "3",
            "ref": [
              "s2cart.cscart_products_categories.category_id"
            ],
            "rows_examined_per_scan": 1,
            "rows_produced_per_join": 8,
            "filtered": "5.00",
            "cost_info": {
              "read_cost": "40.00",
              "eval_cost": "0.80",
              "prefix_cost": "168.01",
              "data_read_per_join": "28K"
            },
            "used_columns": [
              "category_id",
              "usergroup_ids",
              "status",
              "storefront_id"
            ],
            "attached_condition": "((`s2cart`.`cscart_categories`.`storefront_id` in (0,1)) and ((`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')))"
          }
        }
      ]
    }
  }
}