SELECT 
  category_id, 
  category 
FROM 
  cscart_category_descriptions 
WHERE 
  category_id IN (166, 175, 186) 
  AND lang_code = 'en'

Query time 0.00039

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "9.04"
    },
    "table": {
      "table_name": "cscart_category_descriptions",
      "access_type": "ALL",
      "rows_examined_per_scan": 84,
      "rows_produced_per_join": 2,
      "filtered": "3.00",
      "cost_info": {
        "read_cost": "8.79",
        "eval_cost": "0.25",
        "prefix_cost": "9.04",
        "data_read_per_join": "7K"
      },
      "used_columns": [
        "category_id",
        "lang_code",
        "category"
      ],
      "attached_condition": "((`mobikul_delivery_boy_livedemo`.`cscart_category_descriptions`.`category_id` in (166,175,186)) and (`mobikul_delivery_boy_livedemo`.`cscart_category_descriptions`.`lang_code` = 'en'))"
    }
  }
}