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 (
    1273, 1134, 607, 1092, 584, 1132, 446, 
    492, 461, 399, 649, 1129, 930, 931, 977, 
    929, 1020, 928, 749, 40, 416, 405, 427, 
    444, 827, 826, 595, 485, 486, 838, 549, 
    660, 546, 1260, 978, 979, 401, 400, 457, 
    462, 516, 564, 321, 989, 987, 988, 748, 
    502
  ) 
  AND cscart_product_descriptions.lang_code = 'en'

Query time 0.00158

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": 48,
      "filtered": 100,
      "index_condition": "cscart_product_descriptions.product_id in (1273,1134,607,1092,584,1132,446,492,461,399,649,1129,930,931,977,929,1020,928,749,40,416,405,427,444,827,826,595,485,486,838,549,660,546,1260,978,979,401,400,457,462,516,564,321,989,987,988,748,502) and cscart_product_descriptions.lang_code = 'en'"
    }
  }
}

Result

product_id short_description full_description meta_keywords meta_description search_words promo_text unit_name
40
321
399
400
401
405
416
427
444
446
457
461
462
485
486
492
502
516
546
549
564
584
595
607
649
660
748
749
826
827
838
928
929
930
931
977
978
979
987
988
989
1020
1092
1129
1132
1134
1260
1273