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 (
    94342, 94343, 94344, 94345, 94346, 94347, 
    94348, 94349, 94350, 94351, 94352, 
    94353, 94354, 94355, 94356, 94357, 
    94358, 94359, 94360, 94361, 94362, 
    94363, 94364, 94365, 94366, 94435, 
    94442, 94443, 94444, 94445, 94446, 
    94592, 94593, 94594, 94650, 94662, 
    94766, 94767, 94768, 94769, 94770, 
    94771, 94772, 94773, 94774, 94775, 
    94776, 94777
  ) 
  AND cscart_product_descriptions.lang_code = 'en'

Query time 0.00092

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 (94342,94343,94344,94345,94346,94347,94348,94349,94350,94351,94352,94353,94354,94355,94356,94357,94358,94359,94360,94361,94362,94363,94364,94365,94366,94435,94442,94443,94444,94445,94446,94592,94593,94594,94650,94662,94766,94767,94768,94769,94770,94771,94772,94773,94774,94775,94776,94777)) and (`nuie_scalesta_net`.`cscart_product_descriptions`.`lang_code` = 'en'))"
    }
  }
}

Result

product_id short_description full_description
94342
94343
94344
94345
94346
94347
94348
94349
94350
94351
94352
94353
94354
94355
94356
94357
94358
94359
94360
94361
94362
94363
94364
94365
94366
94435
94442
94443
94444
94445
94446
94592
94593
94594
94650
94662
94766
94767
94768
94769
94770
94771
94772
94773
94774
94775
94776
94777