SELECT 
  cscart_product_descriptions.product_id, 
  cscart_product_descriptions.short_description, 
  IF(
    cscart_product_descriptions.short_description = '' 
    OR cscart_product_descriptions.short_description IS NULL, 
    cscart_product_descriptions.full_description, 
    ''
  ) AS full_description, 
  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 (
    10407, 10408, 10409, 10410, 10411, 10412, 
    12853, 12854, 12855, 10414, 10415, 
    10416, 12856, 10417, 10418, 10419, 
    10420, 10421, 10422, 10423
  ) 
  AND cscart_product_descriptions.lang_code = 'ru'

Query time 0.00049

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 (10407,10408,10409,10410,10411,10412,12853,12854,12855,10414,10415,10416,12856,10417,10418,10419,10420,10421,10422,10423) and cscart_product_descriptions.lang_code = 'ru'"
    }
  }
}

Result

product_id short_description full_description meta_keywords meta_description search_words promo_text unit_name
10407
10408
10409
10410
10411
10412
10414
10415
10416
10417
10418
10419
10420
10421
10422
10423
12853
12854
12855
12856