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 (
    397, 511, 1023, 1022, 847, 525, 577, 576, 
    658, 659, 932, 656, 657, 376, 540, 592, 
    1015, 767, 1088, 572, 619, 355, 342, 
    547, 591, 902, 323, 757, 1236, 1225, 
    294, 47, 48, 356, 1293, 1242, 846, 593, 
    616, 1087, 520, 548, 899
  ) 
  AND cscart_product_descriptions.lang_code = 'en'

Query time 0.00151

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": 43,
      "filtered": 100,
      "index_condition": "cscart_product_descriptions.product_id in (397,511,1023,1022,847,525,577,576,658,659,932,656,657,376,540,592,1015,767,1088,572,619,355,342,547,591,902,323,757,1236,1225,294,47,48,356,1293,1242,846,593,616,1087,520,548,899) and cscart_product_descriptions.lang_code = 'en'"
    }
  }
}

Result

product_id short_description full_description meta_keywords meta_description search_words promo_text unit_name
47
48
294
323
342
355
356
376
397
511
520
525
540
547
548
572
576
577
591
592
593
616
619
656
657
658
659
757
767
846
847
899
902
932
1015
1022
1023
1087
1088
1225
1236
1242
1293