SELECT 
  cscart_product_descriptions.product_id, 
  cscart_product_descriptions.unit_name 
FROM 
  cscart_product_descriptions 
WHERE 
  cscart_product_descriptions.product_id IN (
    10481, 10492, 10494, 10495, 10496, 10497, 
    10498, 10499, 10505, 10506, 10507, 
    10516, 10517, 10522, 10523, 10524
  ) 
  AND cscart_product_descriptions.lang_code = 'ru'

Query time 0.00032

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 (10481,10492,10494,10495,10496,10497,10498,10499,10505,10506,10507,10516,10517,10522,10523,10524) and cscart_product_descriptions.lang_code = 'ru'"
    }
  }
}