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 (
    94963, 94964, 95394, 95395, 95396, 95397, 
    95398, 95424, 95425, 95426, 95427, 
    95428, 95429, 95430, 95431, 95432, 
    95433, 95488, 95489, 95490, 95491, 
    95492, 95493, 95497, 95498, 95499, 
    95500, 95501, 95502, 95503
  ) 
  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 (94963,94964,95394,95395,95396,95397,95398,95424,95425,95426,95427,95428,95429,95430,95431,95432,95433,95488,95489,95490,95491,95492,95493,95497,95498,95499,95500,95501,95502,95503)) and (`nuie_scalesta_net`.`cscart_product_descriptions`.`lang_code` = 'en'))"
    }
  }
}

Result

product_id short_description full_description
94963
94964
95394
95395
95396
95397
95398
95424
95425
95426
95427
95428
95429
95430
95431
95432
95433
95488
95489
95490
95491
95492
95493
95497
95498
95499
95500
95501
95502
95503