SELECT 
  cscart_product_descriptions.product_id, 
  cscart_product_descriptions.unit_name 
FROM 
  cscart_product_descriptions 
WHERE 
  cscart_product_descriptions.product_id IN (
    22335, 22336, 22337, 22338, 22339, 22340, 
    22341, 22342, 22343, 22344, 22345, 
    22346, 22347, 22348, 22349, 22350
  ) 
  AND cscart_product_descriptions.lang_code = 'ru'

Query time 0.00069

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 (22335,22336,22337,22338,22339,22340,22341,22342,22343,22344,22345,22346,22347,22348,22349,22350) and cscart_product_descriptions.lang_code = 'ru'"
    }
  }
}