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 (
    88904, 86858, 92192, 92193, 92194, 92195, 
    92196, 92204, 92205, 92206, 92207, 
    92208, 92209, 92442, 92443, 92448, 
    92147, 92148, 92149, 92349, 92350, 
    92351, 92352, 86864
  ) 
  AND cscart_product_descriptions.lang_code = 'en'

Query time 0.00103

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "10.82"
    },
    "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": 24,
      "rows_produced_per_join": 24,
      "filtered": "100.00",
      "cost_info": {
        "read_cost": "8.42",
        "eval_cost": "2.40",
        "prefix_cost": "10.82",
        "data_read_per_join": "91K"
      },
      "used_columns": [
        "product_id",
        "lang_code",
        "short_description",
        "full_description"
      ],
      "attached_condition": "((`nuie_scalesta_net`.`cscart_product_descriptions`.`product_id` in (88904,86858,92192,92193,92194,92195,92196,92204,92205,92206,92207,92208,92209,92442,92443,92448,92147,92148,92149,92349,92350,92351,92352,86864)) and (`nuie_scalesta_net`.`cscart_product_descriptions`.`lang_code` = 'en'))"
    }
  }
}

Result

product_id short_description full_description
86858 Round Shower Ring Curtain Not Supplied
86864 Full Shower Curtain Ring
88904 nuie Shingle Back To Wall Bath Panel - White
92147 BC Designs Standpipes Traditional Cast Freestanding Bath Legs - 660mm x 40mm - Copper
92148 BC Designs Standpipes Traditional Cast Freestanding Bath Legs - 660mm x 40mm - Gold
92149 BC Designs Standpipes Traditional Cast Freestanding Bath Legs - 660mm x 40mm - Nickel
92192 BC Designs Bath Wastes Plug & Chain Exposed Ext Bath Waste - Brushed Chrome
92193 BC Designs Bath Wastes Plug & Chain Exposed Ext Bath Waste - Brushed Gold
92194 BC Designs Bath Wastes Plug & Chain Exposed Ext Bath Waste - Brushed Nickel
92195 BC Designs Bath Wastes Plug & Chain Exposed Ext Bath Waste - Gold
92196 BC Designs Bath Wastes Plug & Chain Exposed Ext Bath Waste - Nickel
92204 BC Designs Bath Wastes Push Down Exposed Bath Waste - Brushed Chrome
92205 BC Designs Bath Wastes Push Down Exposed Bath Waste - Brushed Gold
92206 BC Designs Bath Wastes Push Down Exposed Bath Waste - Brushed Nickel
92207 BC Designs Bath Wastes Push Down Exposed Bath Waste - Copper
92208 BC Designs Bath Wastes Push Down Exposed Bath Waste - Gold
92209 BC Designs Bath Wastes Push Down Exposed Bath Waste - Nickel
92349 BC Designs Standpipes 660x40 Freestanding Legs - Brushed Chrome
92350 BC Designs Standpipes 660x40 Freestanding Legs - Brushed Copper
92351 BC Designs Standpipes 660x40 Freestanding Legs - Brushed Gold
92352 BC Designs Standpipes 660x40 Freestanding Legs - Brushed Nickel
92442 BC Designs Plug & Chain Exposed Bath Waste - Brushed Copper
92443 BC Designs Plug & Chain Exposed Bath Waste - Copper
92448 BC Designs Push Down Exposed Bath Waste - Brushed Copper