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 
FROM 
  cscart_product_descriptions 
WHERE 
  cscart_product_descriptions.product_id IN (
    98857, 98858, 98874, 98875, 98876, 98877, 
    98897, 98914, 98915, 98916, 98917, 
    98918, 98919, 98920, 98921, 98922, 
    98923, 98924, 98925, 98926, 98927, 
    98928, 98929, 98930, 98931, 98932, 
    98933, 98934, 98935, 98936, 98937, 
    98938, 98939, 98940, 98941, 98942, 
    98943, 98944, 98945, 98946, 98947, 
    98948, 98949, 98950, 98951, 98952, 
    98953, 98954
  ) 
  AND cscart_product_descriptions.lang_code = 'en'

Query time 0.00097

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "21.63"
    },
    "table": {
      "table_name": "cscart_product_descriptions",
      "access_type": "range",
      "possible_keys": [
        "PRIMARY",
        "product_id"
      ],
      "key": "PRIMARY",
      "used_key_parts": [
        "product_id",
        "lang_code"
      ],
      "key_length": "9",
      "rows_examined_per_scan": 48,
      "rows_produced_per_join": 48,
      "filtered": "100.00",
      "cost_info": {
        "read_cost": "16.83",
        "eval_cost": "4.80",
        "prefix_cost": "21.63",
        "data_read_per_join": "183K"
      },
      "used_columns": [
        "product_id",
        "lang_code",
        "short_description",
        "full_description"
      ],
      "attached_condition": "((`nuie_scalesta_net`.`cscart_product_descriptions`.`product_id` in (98857,98858,98874,98875,98876,98877,98897,98914,98915,98916,98917,98918,98919,98920,98921,98922,98923,98924,98925,98926,98927,98928,98929,98930,98931,98932,98933,98934,98935,98936,98937,98938,98939,98940,98941,98942,98943,98944,98945,98946,98947,98948,98949,98950,98951,98952,98953,98954)) and (`nuie_scalesta_net`.`cscart_product_descriptions`.`lang_code` = 'en'))"
    }
  }
}

Result

product_id short_description full_description
98857
98858
98874
98875
98876
98877
98897
98914
98915
98916
98917
98918
98919
98920
98921
98922
98923
98924
98925
98926
98927
98928
98929
98930
98931
98932
98933
98934
98935
98936
98937
98938
98939
98940
98941
98942
98943
98944
98945
98946
98947
98948
98949
98950
98951
98952
98953
98954