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 (
    89466, 89474, 89482, 85681, 89458, 85728, 
    85745, 85755, 85765, 87463, 87550, 
    88497, 85735, 84773, 84786, 84795, 
    88199, 88211, 84777, 88196, 88208, 
    88498, 85725, 85742, 85752, 85762, 
    85732, 87513, 87529, 88451
  ) 
  AND cscart_product_descriptions.lang_code = 'en'

Query time 0.00100

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 (89466,89474,89482,85681,89458,85728,85745,85755,85765,87463,87550,88497,85735,84773,84786,84795,88199,88211,84777,88196,88208,88498,85725,85742,85752,85762,85732,87513,87529,88451)) and (`nuie_scalesta_net`.`cscart_product_descriptions`.`lang_code` = 'en'))"
    }
  }
}

Result

product_id short_description full_description
84773 Classique Components Wall Hung 1 Drawer Unit, 600mm - Satin Anthracite
84777 Classique Components Wall Hung 1 Drawer Unit, 600mm - Satin White
84786 Classique Components Wall Hung 1 Drawer Unit, 600mm - Satin Grey
84795 Classique Components Wall Hung 1 Drawer Unit, 600mm - Satin Green
85681 nuie Deco 800mm Wall Hung Single Drawer Unit - Satin White
85725 Hudson Reed Fluted 500mm Wall Hung Single Drawer Unit - Satin Anthracite
85728 Hudson Reed Fluted 600mm Wall Hung Single Drawer Unit - Satin Anthracite
85732 Hudson Reed Fluted 500mm Wall Hung Single Drawer Unit - Satin White
85735 Hudson Reed Fluted 600mm Wall Hung Single Drawer Unit - Satin White
85742 Hudson Reed Fluted 500mm Wall Hung Single Drawer Unit - Satin Grey
85745 Hudson Reed Fluted 600mm Wall Hung Single Drawer Unit - Satin Grey
85752 Hudson Reed Fluted 500mm Wall Hung Single Drawer Unit - Satin Blue
85755 Hudson Reed Fluted 600mm Wall Hung Single Drawer Unit - Satin Blue
85762 Hudson Reed Fluted 500mm Wall Hung Single Drawer Unit - Satin Green
85765 Hudson Reed Fluted 600mm Wall Hung Single Drawer Unit - Satin Green
87463 nuie Athena Wall Hung 1 Drawer Vanity Unit 600mm - Gloss Grey
87513 nuie Athena Wall Hung 1 Drawer Vanity Unit 800mm - Anthracite Woodgrain
87529 nuie Athena Wall Hung 1 Drawer Vanity Unit 800mm - Hacienda Black
87550 nuie Athena Wall Hung 2 Drawer Vanity Unit 500mm - Gloss White
88196 Hudson Reed Juno 600mm Wall Hung Single Drawer Unit - Graphite Grey
88199 Hudson Reed Juno 800mm Wall Hung Single Drawer Unit - Graphite Grey
88208 Hudson Reed Juno 600mm Wall Hung Single Drawer Unit - Coastal Grey
88211 Hudson Reed Juno 800mm Wall Hung Single Drawer Unit - Coastal Grey
88451 nuie Arno 800mm Wall Hung 1-Drawer Unit - Solace Oak
88497 nuie Arno 600mm Wall Hung Single Drawer Unit - Satin Green
88498 nuie Arno 600mm Wall Hung 2-Door Unit - Satin Green
89458 Lunar Components Wall Hung 1 Drawer Unit, 600mm - Satin White
89466 Lunar Components Wall Hung 1 Drawer Unit, 600mm - Satin Grey
89474 Lunar Components Wall Hung 1 Drawer Unit, 600mm - Satin Blue
89482 Lunar Components Wall Hung 1 Drawer Unit, 600mm - Satin Green