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 (
    94693, 94710, 94711, 94712, 94713, 94714, 
    94715, 94716, 96302, 96303, 96711, 
    96712, 96713, 96714, 96716, 96721, 
    96722, 96723, 96725, 96728, 96729, 
    96730, 96731, 96736, 96737, 96750, 
    96752, 96753, 96754, 96755, 96767, 
    96768, 96769, 96770, 96788, 97011, 
    97012, 97013, 97014, 97018, 97019, 
    97020, 97021, 97034, 97035, 97036, 
    97037, 97038
  ) 
  AND cscart_product_descriptions.lang_code = 'en'

Query time 0.00077

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 (94693,94710,94711,94712,94713,94714,94715,94716,96302,96303,96711,96712,96713,96714,96716,96721,96722,96723,96725,96728,96729,96730,96731,96736,96737,96750,96752,96753,96754,96755,96767,96768,96769,96770,96788,97011,97012,97013,97014,97018,97019,97020,97021,97034,97035,97036,97037,97038)) and (`nuie_scalesta_net`.`cscart_product_descriptions`.`lang_code` = 'en'))"
    }
  }
}

Result

product_id short_description full_description
94693
94710
94711
94712
94713
94714
94715
94716
96302
96303
96711
96712
96713
96714
96716
96721
96722
96723
96725
96728
96729
96730
96731
96736
96737
96750
96752
96753
96754
96755
96767
96768
96769
96770
96788
97011
97012
97013
97014
97018
97019
97020
97021
97034
97035
97036
97037
97038