SELECT 
  cscart_product_descriptions.product_id, 
  cscart_product_descriptions.unit_name 
FROM 
  cscart_product_descriptions 
WHERE 
  cscart_product_descriptions.product_id IN (
    22415, 22416, 22417, 22418, 22419, 22420, 
    22421, 22422, 22423, 22424, 22425, 
    22426, 22427, 22428, 22429, 22430
  ) 
  AND cscart_product_descriptions.lang_code = 'ru'

Query time 0.00034

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 (22415,22416,22417,22418,22419,22420,22421,22422,22423,22424,22425,22426,22427,22428,22429,22430) and cscart_product_descriptions.lang_code = 'ru'"
    }
  }
}