SELECT 
  COUNT(*) 
FROM 
  cscart_categories 
WHERE 
  category_id = 250 
  AND storefront_id IN (0, 1)

Query time 0.00044

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "9.25"
    },
    "table": {
      "table_name": "cscart_categories",
      "access_type": "ALL",
      "rows_examined_per_scan": 84,
      "rows_produced_per_join": 1,
      "filtered": "2.00",
      "cost_info": {
        "read_cost": "9.08",
        "eval_cost": "0.17",
        "prefix_cost": "9.25",
        "data_read_per_join": "4K"
      },
      "used_columns": [
        "category_id",
        "storefront_id"
      ],
      "attached_condition": "((`mobikul_delivery_boy_livedemo`.`cscart_categories`.`category_id` = 250) and (`mobikul_delivery_boy_livedemo`.`cscart_categories`.`storefront_id` in (0,1)))"
    }
  }
}