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 (
    89508, 89515, 89516, 83254, 83256, 83261, 
    83263, 90562, 90563, 90568, 90569, 
    90574, 90575, 86141, 86164, 86649, 
    86718, 85072, 85074, 85158, 85160, 
    85204, 85206, 85250
  ) 
  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 (89508,89515,89516,83254,83256,83261,83263,90562,90563,90568,90569,90574,90575,86141,86164,86649,86718,85072,85074,85158,85160,85204,85206,85250)) and (`nuie_scalesta_net`.`cscart_product_descriptions`.`lang_code` = 'en'))"
    }
  }
}

Result

product_id short_description full_description
83254 nuie Athena Floor Standing 4 Door Vanity With Twin Polymarble Basin 1200mm - Anthracite Woodgrain
83256 nuie Athena Floor Standing 4 Door Vanity With Twin Ceramic Basin 1200mm - Anthracite Woodgrain
83261 nuie Athena Floor Standing 4 Door Vanity With Twin Polymarble Basin 1200mm - Hacienda Black
83263 nuie Athena Floor Standing 4 Door Vanity With Twin Ceramic Basin 1200mm - Hacienda Black
85072 Hudson Reed Fluted 1200mm Wall Hung 2-Drawer Vanity and Double Basin - Satin Anthracite
85074 Hudson Reed Fluted 1200mm Wall Hung 2-Drawer Vanity and Double Basin - Satin Anthracite
85158 Hudson Reed Fluted 1200mm Wall Hung 2-Drawer Vanity and Double Basin - Satin Grey
85160 Hudson Reed Fluted 1200mm Wall Hung 2-Drawer Vanity and Double Basin - Satin Grey
85204 Hudson Reed Fluted 1200mm Wall Hung 2-Drawer Vanity and Double Basin - Satin Blue
85206 Hudson Reed Fluted 1200mm Wall Hung 2-Drawer Vanity and Double Basin - Satin Blue
85250 Hudson Reed Fluted 1200mm Wall Hung 2-Drawer Vanity and Double Basin - Satin Green
86141 Hudson Reed Havana Wall Hung 4 Drawer Unit & Colour Match Worktop, 1200mm - Graphite Grey
86164 Hudson Reed Havana Wall Hung 4 Drawer Unit & Colour Match Worktop, 1200mm - Coastal Grey
86649 Hudson Reed Juno 1200mm Wall Hung 4-Drawer Vanity & Worktop - Graphite Grey
86718 Hudson Reed Juno 1200mm Wall Hung 4-Drawer Vanity & Worktop - Coastal Grey
89508 Hudson Reed Solar Floor Standing 2 Drawer Vanity Unit with Ceramic Basin 600mm - Indigo Blue
89515 Hudson Reed Solar 600mm Floor Standing 2-Drawer Unit and Polymarble 1 Tap Hole Basin - Fern Green
89516 Hudson Reed Solar 600mm Floor Standing 2-Drawer Unit and Ceramic 1 Tap Hole Basin - Fern Green
90562 Nuie Arno 1200mm Floor Standing 4 Door Vanity & Double Basin 1 - Grey Vicenza Oak
90563 Nuie Arno 1200mm Floor Standing 4 Door Vanity & Double Basin 2 - Grey Vicenza Oak
90568 Nuie Arno 1200mm Floor Standing 4 Door Vanity & Double Basin 1 - Anthracite Woodgrain
90569 Nuie Arno 1200mm Floor Standing 4 Door Vanity & Double Basin 2 - Anthracite Woodgrain
90574 Nuie Arno 1200mm Floor Standing 4 Door Vanity & Double Basin 1 - Black Woodgrain
90575 Nuie Arno 1200mm Floor Standing 4 Door Vanity & Double Basin 2 - Black Woodgrain