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 (
    92865, 92866, 92867, 92868, 92869, 92870, 
    92871, 92872, 92873, 92874, 92875, 
    92876, 92877, 92878, 92879, 92880, 
    92881, 92882, 92883, 92884, 92885, 
    92886, 92887, 92888, 92889, 92890, 
    92891, 92946, 92947, 92948
  ) 
  AND cscart_product_descriptions.lang_code = 'en'

Query time 0.00113

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 (92865,92866,92867,92868,92869,92870,92871,92872,92873,92874,92875,92876,92877,92878,92879,92880,92881,92882,92883,92884,92885,92886,92887,92888,92889,92890,92891,92946,92947,92948)) and (`nuie_scalesta_net`.`cscart_product_descriptions`.`lang_code` = 'en'))"
    }
  }
}

Result

product_id short_description full_description
92865
92866
92867
92868
92869
92870
92871
92872
92873
92874
92875
92876
92877
92878
92879
92880
92881
92882
92883
92884
92885
92886
92887
92888
92889
92890
92891
92946
92947
92948