SELECT 
  cscart_product_descriptions.product_id, 
  cscart_product_descriptions.unit_name 
FROM 
  cscart_product_descriptions 
WHERE 
  cscart_product_descriptions.product_id IN (
    22063, 22064, 22065, 22066, 22067, 22068, 
    22069, 22070, 22071, 22072, 22073, 
    22074, 22075, 22076, 22077, 22078
  ) 
  AND cscart_product_descriptions.lang_code = 'ru'

Query time 0.00065

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 (22063,22064,22065,22066,22067,22068,22069,22070,22071,22072,22073,22074,22075,22076,22077,22078) and cscart_product_descriptions.lang_code = 'ru'"
    }
  }
}