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 (
    97688, 97689, 97690, 97691, 97692, 97693, 
    97694, 97695, 97696, 97707, 97708, 
    97709, 97710, 97711, 97712, 97728, 
    97729, 97730, 97731, 97732, 97733, 
    97734, 97735, 97736, 97737, 97738, 
    97739, 97740, 97741, 97742, 97743, 
    97744, 97745, 97746, 97747, 97748, 
    97749, 97750, 97751, 97752, 97753, 
    97754, 97755, 97756, 97757, 97758, 
    97759, 97760
  ) 
  AND cscart_product_descriptions.lang_code = 'en'

Query time 0.00095

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "26.88"
    },
    "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": "22.08",
        "eval_cost": "4.80",
        "prefix_cost": "26.88",
        "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 (97688,97689,97690,97691,97692,97693,97694,97695,97696,97707,97708,97709,97710,97711,97712,97728,97729,97730,97731,97732,97733,97734,97735,97736,97737,97738,97739,97740,97741,97742,97743,97744,97745,97746,97747,97748,97749,97750,97751,97752,97753,97754,97755,97756,97757,97758,97759,97760)) and (`nuie_scalesta_net`.`cscart_product_descriptions`.`lang_code` = 'en'))"
    }
  }
}

Result

product_id short_description full_description
97688
97689
97690
97691
97692
97693
97694
97695
97696
97707
97708
97709
97710
97711
97712
97728
97729
97730
97731
97732
97733
97734
97735
97736
97737
97738
97739
97740
97741
97742
97743
97744
97745
97746
97747
97748
97749
97750
97751
97752
97753
97754
97755
97756
97757
97758
97759
97760