SELECT 
  cscart_product_descriptions.product_id, 
  cscart_product_descriptions.unit_name 
FROM 
  cscart_product_descriptions 
WHERE 
  cscart_product_descriptions.product_id IN (
    22271, 22272, 22273, 22274, 22275, 22276, 
    22277, 22278, 22279, 22280, 22281, 
    22282, 22283, 22284, 22285, 22286
  ) 
  AND cscart_product_descriptions.lang_code = 'ru'

Query time 0.00038

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "table_name": "cscart_product_descriptions",
      "access_type": "range",
      "possible_keys": ["PRIMARY", "product_id", "idx_product_lang"],
      "key": "PRIMARY",
      "key_length": "9",
      "used_key_parts": ["product_id", "lang_code"],
      "rows": 16,
      "filtered": 100,
      "index_condition": "cscart_product_descriptions.product_id in (22271,22272,22273,22274,22275,22276,22277,22278,22279,22280,22281,22282,22283,22284,22285,22286) and cscart_product_descriptions.lang_code = 'ru'"
    }
  }
}