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 (
    94906, 94907, 94908, 94909, 94910, 94911, 
    94912, 94913, 94914, 94915, 94916, 
    94917, 94918, 94919, 94920, 94921, 
    94922, 94923, 94924, 94925, 94926, 
    94927, 94928, 94929, 94930, 94931, 
    94932, 94933, 94934, 94935
  ) 
  AND cscart_product_descriptions.lang_code = 'en'

Query time 0.00070

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 (94906,94907,94908,94909,94910,94911,94912,94913,94914,94915,94916,94917,94918,94919,94920,94921,94922,94923,94924,94925,94926,94927,94928,94929,94930,94931,94932,94933,94934,94935)) and (`nuie_scalesta_net`.`cscart_product_descriptions`.`lang_code` = 'en'))"
    }
  }
}

Result

product_id short_description full_description
94906
94907
94908
94909
94910
94911
94912
94913
94914
94915
94916
94917
94918
94919
94920
94921
94922
94923
94924
94925
94926
94927
94928
94929
94930
94931
94932
94933
94934
94935