SELECT 
  cscart_product_descriptions.product_id, 
  cscart_product_descriptions.unit_name 
FROM 
  cscart_product_descriptions 
WHERE 
  cscart_product_descriptions.product_id IN (
    22447, 22448, 22449, 22450, 22451, 22452, 
    22453, 22454, 22455, 22456, 22457, 
    22458, 22459, 22460, 22461, 22462
  ) 
  AND cscart_product_descriptions.lang_code = 'ru'

Query time 0.00043

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 (22447,22448,22449,22450,22451,22452,22453,22454,22455,22456,22457,22458,22459,22460,22461,22462) and cscart_product_descriptions.lang_code = 'ru'"
    }
  }
}