SELECT 
  cscart_product_descriptions.product_id, 
  cscart_product_descriptions.unit_name 
FROM 
  cscart_product_descriptions 
WHERE 
  cscart_product_descriptions.product_id IN (
    3173, 3172, 3170, 3162, 2508, 2507, 2506, 
    2505, 2504, 2503, 2287, 2277
  ) 
  AND cscart_product_descriptions.lang_code = 'en'

Query time 0.00064

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "5.41"
    },
    "table": {
      "table_name": "cscart_product_descriptions",
      "access_type": "range",
      "possible_keys": [
        "PRIMARY",
        "product_id"
      ],
      "key": "PRIMARY",
      "used_key_parts": [
        "product_id",
        "lang_code"
      ],
      "key_length": "9",
      "rows_examined_per_scan": 12,
      "rows_produced_per_join": 12,
      "filtered": "100.00",
      "cost_info": {
        "read_cost": "4.22",
        "eval_cost": "1.20",
        "prefix_cost": "5.42",
        "data_read_per_join": "54K"
      },
      "used_columns": [
        "product_id",
        "lang_code",
        "unit_name"
      ],
      "attached_condition": "((`aomnia_com`.`cscart_product_descriptions`.`product_id` in (3173,3172,3170,3162,2508,2507,2506,2505,2504,2503,2287,2277)) and (`aomnia_com`.`cscart_product_descriptions`.`lang_code` = 'en'))"
    }
  }
}