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 (
    982, 981, 983, 828, 421, 647, 315, 624, 
    937, 1131, 671, 670, 42, 43, 1051, 936, 
    935, 599, 900, 44, 404, 835, 836, 1263, 
    322, 311, 312, 744, 742, 837, 537, 839, 
    621, 1048, 1049, 1014, 575, 1034, 1243, 
    1073, 1295, 497, 704, 700, 702, 705, 
    709, 698, 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 0.00256

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": 96,
      "filtered": 100,
      "index_condition": "cscart_product_descriptions.product_id in (982,981,983,828,421,647,315,624,937,1131,671,670,42,43,1051,936,935,599,900,44,404,835,836,1263,322,311,312,744,742,837,537,839,621,1048,1049,1014,575,1034,1243,1073,1295,497,704,700,702,705,709,698,1273,1134,607,1092,584,1132,446,492,461,399,649,1129,930,931,977,929,1020,928,749,40,416,405,427,444,827,826,595,485,486,838,549,660,546,1260,978,979,401,400,457,462,516,564,321,989,987,988,748,502) 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
42
43
44
311
312
315
321
322
399
400
401
404
405
416
421
427
444
446
457
461
462
485
486
492
497
502
516
537
546
549
564
575
584
595
599
607
621
624
647
649
660
670
671
698
700
702
704
705
709
742
744
748
749
826
827
828
835
836
837
838
839
900
928
929
930
931
935
936
937
977
978
979
981
982
983
987
988
989
1014
1020
1034
1048
1049
1051
1073
1092
1129
1131
1132
1134
1243
1260
1263
1273
1295