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 (
    90990, 85084, 85085, 85170, 85171, 85216, 
    85217, 85262, 85263, 85314, 85411, 
    85462, 85513, 85317, 85318, 85414, 
    85415, 85465, 85466, 85516, 85517, 
    86471, 86472, 86747
  ) 
  AND cscart_product_descriptions.lang_code = 'en'

Query time 0.00074

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 (90990,85084,85085,85170,85171,85216,85217,85262,85263,85314,85411,85462,85513,85317,85318,85414,85415,85465,85466,85516,85517,86471,86472,86747)) and (`nuie_scalesta_net`.`cscart_product_descriptions`.`lang_code` = 'en'))"
    }
  }
}

Result

product_id short_description full_description
85084 Hudson Reed Fluted 800mm Wall Hung 2-Drawer Vanity and Laminate Top - Satin Anthracite
85085 Hudson Reed Fluted 800mm Wall Hung 2-Drawer Vanity and Laminate Top - Satin Anthracite
85170 Hudson Reed Fluted 800mm Wall Hung 2-Drawer Vanity and Laminate Top - Satin Grey
85171 Hudson Reed Fluted 800mm Wall Hung 2-Drawer Vanity and Laminate Top - Satin Grey
85216 Hudson Reed Fluted 800mm Wall Hung 2-Drawer Vanity and Laminate Top - Satin Blue
85217 Hudson Reed Fluted 800mm Wall Hung 2-Drawer Vanity and Laminate Top - Satin Blue
85262 Hudson Reed Fluted 800mm Wall Hung 2-Drawer Vanity and Laminate Top - Satin Green
85263 Hudson Reed Fluted 800mm Wall Hung 2-Drawer Vanity and Laminate Top - Satin Green
85314 nuie Deco 1200mm Wall Hung 2-Drawer Vanity & Worktop - Satin Anthracite
85317 nuie Deco 800mm Wall Hung 2-Drawer Vanity & Thin-Edge Basin - Satin Anthracite
85318 nuie Deco 800mm Wall Hung 2-Drawer Vanity & Curved Basin - Satin Anthracite
85411 nuie Deco 1200mm Wall Hung 2-Drawer Vanity & Worktop - Satin Grey
85414 nuie Deco 800mm Wall Hung 2-Drawer Vanity & Thin-Edge Basin - Satin Grey
85415 nuie Deco 800mm Wall Hung 2-Drawer Vanity & Curved Basin - Satin Grey
85462 nuie Deco 1200mm Wall Hung 2-Drawer Vanity & Worktop - Satin Blue
85465 nuie Deco 800mm Wall Hung 2-Drawer Vanity & Thin-Edge Basin - Satin Blue
85466 nuie Deco 800mm Wall Hung 2-Drawer Vanity & Curved Basin - Satin Blue
85513 nuie Deco 1200mm Wall Hung 2-Drawer Vanity & Worktop - Satin Green
85516 nuie Deco 800mm Wall Hung 2-Drawer Vanity & Thin-Edge Basin - Satin Green
85517 nuie Deco 800mm Wall Hung 2-Drawer Vanity & Curved Basin - Satin Green
86471 Hudson Reed Juno 800mm Floor Standing 2-Door Vanity & Thin-Edge 1 Tap Hole Basin - Autumn Oak
86472 Hudson Reed Juno 800mm Floor Standing 2-Door Vanity & Curved 1 Tap Hole Basin - Autumn Oak
86747 Hudson Reed Juno Floor Standing 2 Door Vanity Basin Unit & Thin-Edge Ceramic Basin, 800mm - Metallic Slate
90990 nuie Arno Wall Hung 2 Drawer Vanity & Laminate Worktop, 800mm - Satin Grey/Sparkle White