SELECT 
  cscart_product_descriptions.product_id, 
  cscart_product_descriptions.unit_name 
FROM 
  cscart_product_descriptions 
WHERE 
  cscart_product_descriptions.product_id IN (
    22015, 22016, 22017, 22018, 22019, 22020, 
    22021, 22022, 22023, 22024, 22025, 
    22026, 22027, 22028, 22029, 22030
  ) 
  AND cscart_product_descriptions.lang_code = 'ru'

Query time 0.00978

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 (22015,22016,22017,22018,22019,22020,22021,22022,22023,22024,22025,22026,22027,22028,22029,22030) and cscart_product_descriptions.lang_code = 'ru'"
    }
  }
}