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 (
    93465, 93466, 93467, 93468, 93469, 93470, 
    93471, 93472, 93473, 93474, 93475, 
    93476, 93477, 93478, 93479, 93480, 
    93481, 93482, 93483, 93484, 93485, 
    93486, 93487, 93488, 93489, 93490, 
    93491, 93492, 93493, 93494
  ) 
  AND cscart_product_descriptions.lang_code = 'en'

Query time 0.00090

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 (93465,93466,93467,93468,93469,93470,93471,93472,93473,93474,93475,93476,93477,93478,93479,93480,93481,93482,93483,93484,93485,93486,93487,93488,93489,93490,93491,93492,93493,93494)) and (`nuie_scalesta_net`.`cscart_product_descriptions`.`lang_code` = 'en'))"
    }
  }
}

Result

product_id short_description full_description
93465
93466
93467
93468
93469
93470
93471
93472
93473
93474
93475
93476
93477
93478
93479
93480
93481
93482
93483
93484
93485
93486
93487
93488
93489
93490
93491
93492
93493
93494