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 (
    84673, 84674, 84656, 84318, 84536, 84537, 
    84602, 84603, 89035, 84492, 84296, 
    84541, 84542, 84607, 84608, 84671, 
    84672, 84645, 84524, 84590, 84338, 
    84339, 84326, 84539, 84605, 87392, 
    87393, 84343, 84344, 84627
  ) 
  AND cscart_product_descriptions.lang_code = 'en'

Query time 0.00076

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 (84673,84674,84656,84318,84536,84537,84602,84603,89035,84492,84296,84541,84542,84607,84608,84671,84672,84645,84524,84590,84338,84339,84326,84539,84605,87392,87393,84343,84344,84627)) and (`nuie_scalesta_net`.`cscart_product_descriptions`.`lang_code` = 'en'))"
    }
  }
}

Result

product_id short_description full_description
84296 Hudson Reed Fusion Floor Standing WC Unit & Top 500mm - Gloss White
84318 Hudson Reed Fusion Floor Standing 1 Door Vanity Unit & Polymarble Basin 400mm - Gloss White
84326 Hudson Reed Fusion Wall Hung 2 Door Vanity Unit & Polymarble Basin 600mm - Gloss White
84338 Hudson Reed Fusion Wall Hung 4 Door Vanity Unit & Polymarble Basin Compact 1200mm - Gloss White
84339 Hudson Reed Fusion Wall Hung 2 Door Vanity Unit & Ceramic Basin 600mm - Gloss White
84343 Hudson Reed Fusion Wall Hung 2 Door Vanity Unit & Polymarble Basin 500mm - Gloss White
84344 Hudson Reed Fusion Wall Hung 2 Door Vanity Unit & Ceramic Basin 500mm - Gloss White
84492 Hudson Reed Fusion Floor Standing WC Unit & Top Compact 500mm - Anthracite Woodgrain
84524 Hudson Reed Fusion Wall Hung 2 Door Vanity Unit & Polymarble Basin 600mm - Anthracite Woodgrain
84536 Hudson Reed Fusion Wall Hung 4 Door Vanity Unit & Polymarble Basin Compact 1200mm - Anthracite Woodgrain
84537 Hudson Reed Fusion Wall Hung 2 Door Vanity Unit & Ceramic Basin 600mm - Anthracite Woodgrain
84539 Hudson Reed Fusion Wall Hung 2 Door Vanity Unit & Polymarble Basin Compact 500mm - Anthracite Woodgrain
84541 Hudson Reed Fusion Wall Hung 2 Door Vanity Unit & Polymarble Basin 500mm - Anthracite Woodgrain
84542 Hudson Reed Fusion Wall Hung 2 Door Vanity Unit & Ceramic Basin 500mm - Anthracite Woodgrain
84590 Hudson Reed Fusion Wall Hung 2 Door Vanity Unit & Polymarble Basin 600mm - Hacienda Black
84602 Hudson Reed Fusion Wall Hung 4 Door Vanity Unit & Polymarble Basin Compact 1200mm - Hacienda Black
84603 Hudson Reed Fusion Wall Hung 2 Door Vanity Unit & Ceramic Basin 600mm - Hacienda Black
84605 Hudson Reed Fusion Wall Hung 2 Door Vanity Unit & Polymarble Basin Compact 500mm - Hacienda Black
84607 Hudson Reed Fusion Wall Hung 2 Door Vanity Unit & Polymarble Basin 500mm - Hacienda Black
84608 Hudson Reed Fusion Wall Hung 2 Door Vanity Unit & Ceramic Basin 500mm - Hacienda Black
84627 Hudson Reed Fusion Floor Standing WC Unit with Coordinating Top 500mm - Gloss Grey
84645 Hudson Reed Fusion Floor Standing WC Unit with Coordinating Top 600mm - Gloss Grey
84656 Hudson Reed Fusion Wall Hung 2 Door Vanity Unit & Polymarble Basin 600mm - Gloss Grey
84671 Hudson Reed Fusion Wall Hung 2 Door Vanity Unit & Polymarble Basin Compact 500mm - Gloss Grey
84672 Hudson Reed Fusion Wall Hung 1 Door Vanity Unit & Polymarble Basin 400mm - Gloss Grey
84673 Hudson Reed Fusion Wall Hung 2 Door Vanity Unit & Polymarble Basin 500mm - Gloss Grey
84674 Hudson Reed Fusion Wall Hung 2 Door Vanity Unit & Ceramic Basin 500mm - Gloss Grey
87392 nuie Merit Wall Hung Single Door Vanity and Ceramic Basin 500mm - Anthracite Woodgrain
87393 nuie Merit Wall Hung Single Door Vanity and Ceramic Basin 500mm - Hacienda Black
89035 nuie Athena Floor Standing 2 in 1 Basin Unit 500mm - Gloss White