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 (
    88316, 88315, 91431, 88314, 88308, 88313, 
    88320, 88322, 92318, 88254, 92319, 
    92321, 92320, 88259, 88256, 88257, 
    85630, 88258, 87872, 92317, 88317, 
    88318, 88011, 88255
  ) 
  AND cscart_product_descriptions.lang_code = 'en'

Query time 0.00091

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 (88316,88315,91431,88314,88308,88313,88320,88322,92318,88254,92319,92321,92320,88259,88256,88257,85630,88258,87872,92317,88317,88318,88011,88255)) and (`nuie_scalesta_net`.`cscart_product_descriptions`.`lang_code` = 'en'))"
    }
  }
}

Result

product_id short_description full_description
85630 nuie Ella Screens L-Shaped Hinged Bath Screen 5mm - Satin Chrome
87872 nuie Pacific Bath Screens Curved B-Bath Screen with Rail 6mm - Polished Chrome
88011 nuie Pacific P-Bath Curved Hinged Shower Bath Screen 6mm - Matt Black
88254 nuie Pacific Bath Screens L-Shaped Bath Screen Double Hinged 6mm - Polished Chrome
88255 nuie Pacific Bath Screens L-Shaped Bath Screen Hinged 6mm - Matt Black
88256 nuie Pacific L-Shaped Abstract Bath Screen with Fixed Return 6mm - Matt Black
88257 nuie Pacific Bath Screens Square Black Framed Bath Screen With Fixed Return 6mm - Matt Black
88258 nuie Pacific Bath Screens Square Bath Screen With Fixed Return 6mm - Matt Black
88259 nuie Pacific Bath Screens L-Shaped Bath Screen Hinged With Rail 6mm - Polished Chrome
88308 nuie Pacific Bath Screens Round Bath Screen With Fixed Panel 6mm - Polished Chrome
88313 nuie Pacific Bath Screens Square Bath Screen With Fixed Panel 6mm - Polished Chrome
88314 nuie Bath Screens Square Hinged Bath Screen 8mm - Polished Chrome
88315 nuie Pacific Square Screens Square Hinged Bath Screen - Brushed Brass
88316 nuie Pacific Square Hinged Abstract Bath Screen 8mm - Matt Black
88317 nuie Pacific Suqare Abstract Bath Screen 6mm - Matt Black
88318 nuie Bath Screens Square Black Framed Bath Screen 6mm - Matt Black
88320 nuie Pacific Bath Screens Square Bath Screen With Fixed Panel & Rail 6mm - Polished Chrome
88322 nuie Pacific Bath Screens Round Bath Screen Fixed Panel & Rail 6mm - Polished Chrome
91431 nuie Pacific Square 8mm Toughened Safety Glass Hinged Shower Bath Screen - Matt Black
92317 BC Designs Square Bath Screen With Rail 1435x790 - Chrome
92318 BC Designs Straight Bath Screen Fixed 1435x1005 - Chrome
92319 BC Designs Curved P Bath Screen 1435x720 - Chrome
92320 BC Designs Fixed L Bath Screen 1400x805 - Chrome
92321 BC Designs Hinged L Bath Screen 1400x808 - Chrome