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 (
    94564, 94565, 94566, 94567, 94568, 94569, 
    94570, 94571, 94572, 94583, 94584, 
    94585, 94586, 94587, 94588, 95830, 
    95831, 95869, 95870, 95871, 95872, 
    95873, 95874, 95875, 95876, 95877, 
    95878, 95879, 95880, 95881
  ) 
  AND cscart_product_descriptions.lang_code = 'en'

Query time 0.00068

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 (94564,94565,94566,94567,94568,94569,94570,94571,94572,94583,94584,94585,94586,94587,94588,95830,95831,95869,95870,95871,95872,95873,95874,95875,95876,95877,95878,95879,95880,95881)) and (`nuie_scalesta_net`.`cscart_product_descriptions`.`lang_code` = 'en'))"
    }
  }
}

Result

product_id short_description full_description
94564
94565
94566
94567
94568
94569
94570
94571
94572
94583
94584
94585
94586
94587
94588
95830
95831
95869
95870
95871
95872
95873
95874
95875
95876
95877
95878
95879
95880
95881