SELECT 
  cscart_product_descriptions.product_id, 
  cscart_product_descriptions.unit_name 
FROM 
  cscart_product_descriptions 
WHERE 
  cscart_product_descriptions.product_id IN (
    22255, 22256, 22257, 22258, 22259, 22260, 
    22261, 22262, 22263, 22264, 22265, 
    22266, 22267, 22268, 22269, 22270
  ) 
  AND cscart_product_descriptions.lang_code = 'ru'

Query time 0.00076

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 (22255,22256,22257,22258,22259,22260,22261,22262,22263,22264,22265,22266,22267,22268,22269,22270) and cscart_product_descriptions.lang_code = 'ru'"
    }
  }
}