SELECT 
  category_id, 
  parent_id 
FROM 
  cscart_categories 
WHERE 
  parent_id IN(
    2835, 2840, 2839, 2838, 2834, 2833, 2837, 
    2841, 2842, 2843, 2844, 2846, 2845, 
    2847, 2850
  ) 
  AND category_id != 414

Query time 0.00043

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "10.51"
    },
    "table": {
      "table_name": "cscart_categories",
      "access_type": "range",
      "possible_keys": [
        "PRIMARY",
        "parent",
        "p_category_id"
      ],
      "key": "parent",
      "used_key_parts": [
        "parent_id"
      ],
      "key_length": "3",
      "rows_examined_per_scan": 15,
      "rows_produced_per_join": 15,
      "filtered": "100.00",
      "index_condition": "(`s2cart`.`cscart_categories`.`parent_id` in (2835,2840,2839,2838,2834,2833,2837,2841,2842,2843,2844,2846,2845,2847,2850))",
      "cost_info": {
        "read_cost": "9.01",
        "eval_cost": "1.50",
        "prefix_cost": "10.51",
        "data_read_per_join": "53K"
      },
      "used_columns": [
        "category_id",
        "parent_id"
      ],
      "attached_condition": "(`s2cart`.`cscart_categories`.`category_id` <> 414)"
    }
  }
}