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 (
    95575, 95576, 95577, 95578, 95579, 95580, 
    95581, 95582, 95583, 95584, 95585, 
    95586, 95587, 95588, 95589, 95590, 
    95591, 95592, 95593, 95594, 95595, 
    95596, 95597, 95598, 95599, 95600, 
    95601, 95602, 95603, 95604
  ) 
  AND cscart_product_descriptions.lang_code = 'en'

Query time 0.00026

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "13.52"
    },
    "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": 30,
      "rows_produced_per_join": 30,
      "filtered": "100.00",
      "cost_info": {
        "read_cost": "10.52",
        "eval_cost": "3.00",
        "prefix_cost": "13.52",
        "data_read_per_join": "114K"
      },
      "used_columns": [
        "product_id",
        "lang_code",
        "short_description",
        "full_description"
      ],
      "attached_condition": "((`nuie_scalesta_net`.`cscart_product_descriptions`.`product_id` in (95575,95576,95577,95578,95579,95580,95581,95582,95583,95584,95585,95586,95587,95588,95589,95590,95591,95592,95593,95594,95595,95596,95597,95598,95599,95600,95601,95602,95603,95604)) and (`nuie_scalesta_net`.`cscart_product_descriptions`.`lang_code` = 'en'))"
    }
  }
}

Result

product_id short_description full_description
95575
95576
95577
95578
95579
95580
95581
95582
95583
95584
95585
95586
95587
95588
95589
95590
95591
95592
95593
95594
95595
95596
95597
95598
95599
95600
95601
95602
95603
95604