SELECT 
  cscart_product_descriptions.product_id, 
  cscart_product_descriptions.unit_name 
FROM 
  cscart_product_descriptions 
WHERE 
  cscart_product_descriptions.product_id IN (
    17438, 37503, 23822, 38852, 67915, 33142, 
    67919, 67921, 67924, 67926
  ) 
  AND cscart_product_descriptions.lang_code = 'ja'

Query time 0.00019

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "table_name": "cscart_product_descriptions",
      "access_type": "range",
      "possible_keys": ["PRIMARY", "product_id"],
      "key": "product_id",
      "key_length": "3",
      "used_key_parts": ["product_id"],
      "rows": 10,
      "filtered": 100,
      "index_condition": "cscart_product_descriptions.product_id in (17438,37503,23822,38852,67915,33142,67919,67921,67924,67926)",
      "attached_condition": "cscart_product_descriptions.lang_code = 'ja'"
    }
  }
}