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 (
    498, 475, 496, 1091, 363, 483, 1072, 1071, 
    1085, 1076, 617, 1043, 887, 477, 634, 
    411, 478, 885, 518, 848, 904, 865, 626, 
    602
  ) 
  AND cscart_product_descriptions.lang_code = 'en'

Query time 0.00115

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": 24,
      "filtered": 100,
      "index_condition": "cscart_product_descriptions.product_id in (498,475,496,1091,363,483,1072,1071,1085,1076,617,1043,887,477,634,411,478,885,518,848,904,865,626,602) and cscart_product_descriptions.lang_code = 'en'"
    }
  }
}

Result

product_id short_description full_description meta_keywords meta_description search_words promo_text unit_name
363
411
475
477
478
483
496
498
518
602
617
626
634
848
865
885
887
904
1043
1071
1072
1076
1085
1091