SELECT 
  cscart_product_descriptions.product_id, 
  cscart_product_descriptions.meta_keywords, 
  cscart_product_descriptions.meta_description, 
  cscart_product_descriptions.search_words, 
  cscart_product_descriptions.promo_text, 
  cscart_product_descriptions.unit_name 
FROM 
  cscart_product_descriptions 
WHERE 
  cscart_product_descriptions.product_id IN (
    9874, 9875, 9887, 9879, 9942, 9943, 9941, 
    9944, 10813, 10814, 10815, 10816, 10817, 
    10818, 10819, 10820, 10821, 10822, 
    10823, 10824
  ) 
  AND cscart_product_descriptions.lang_code = 'ru'

Query time 0.00075

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "table_name": "cscart_product_descriptions",
      "access_type": "range",
      "possible_keys": ["PRIMARY", "product_id"],
      "key": "PRIMARY",
      "key_length": "9",
      "used_key_parts": ["product_id", "lang_code"],
      "rows": 20,
      "filtered": 100,
      "index_condition": "cscart_product_descriptions.product_id in (9874,9875,9887,9879,9942,9943,9941,9944,10813,10814,10815,10816,10817,10818,10819,10820,10821,10822,10823,10824) and cscart_product_descriptions.lang_code = 'ru'"
    }
  }
}