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 (
    87101, 87102, 87103, 87104, 87105, 87106, 
    86913, 86914, 86915, 86916, 86917, 
    86918, 86919, 86974, 86975, 86976, 
    86977, 86978, 86979, 86980, 87035, 
    87036, 87037, 87038, 87039, 87040, 
    87041, 87093, 87094, 87095
  ) 
  AND cscart_product_descriptions.lang_code = 'en'

Query time 0.00094

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 (87101,87102,87103,87104,87105,87106,86913,86914,86915,86916,86917,86918,86919,86974,86975,86976,86977,86978,86979,86980,87035,87036,87037,87038,87039,87040,87041,87093,87094,87095)) and (`nuie_scalesta_net`.`cscart_product_descriptions`.`lang_code` = 'en'))"
    }
  }
}

Result

product_id short_description full_description
86913 Old London Floor Standing 2 Door Vanity Unit with 1 Tap Hole Black Marble Top 600mm - Storm Grey
86914 Old London Floor Standing 2 Door Vanity Unit with 1 Tap Hole White Marble Top 600mm - Storm Grey
86915 Old London Old London Storm Grey Floor Standing 2 Door Vanity Basin Unit with Square Basin & 1 Tap Hole Marble Top, 600mm - Storm Grey
86916 Old London Floor Standing 2 Door Vanity Unit with 1 Tap Hole Grey Marble Top 600mm - Storm Grey
86917 Old London Floor Standing 2 Door Vanity Unit with 3 Tap Hole Black Marble Top 600mm - Storm Grey
86918 Old London Floor Standing 2 Door Vanity Unit with 3 Tap Hole White Marble Top 600mm - Storm Grey
86919 Old London Floor Standing 2 Door Vanity Unit with 3 Tap Hole Grey Marble Top 600mm - Storm Grey
86974 Old London Floor Standing 2 Door Vanity Unit with 1 Tap Hole Black Marble Top 600mm - Twilight Blue
86975 Old London Floor Standing 2 Door Vanity Unit with 1 Tap Hole White Marble Top 600mm - Twilight Blue
86976 Old London Old London Twilight Blue Floor Standing 2 Door Vanity Basin Unit with Square Basin & 1 Tap Hole Marble Top, 600mm - Twilight Blue
86977 Old London Floor Standing 2 Door Vanity Unit with 1 Tap Hole Grey Marble Top 600mm - Twilight Blue
86978 Old London Floor Standing 2 Door Vanity Unit with 3 Tap Hole Black Marble Top 600mm - Twilight Blue
86979 Old London Floor Standing 2 Door Vanity Unit with 3 Tap Hole White Marble Top 600mm - Twilight Blue
86980 Old London Floor Standing 2 Door Vanity Unit with 3 Tap Hole Grey Marble Top 600mm - Twilight Blue
87035 Old London Floor Standing 2 Door Vanity Unit with 1 Tap Hole Black Marble Top 600mm - Timeless Sand
87036 Old London Floor Standing 2 Door Vanity Unit with 1 Tap Hole White Marble Top 600mm - Timeless Sand
87037 Old London Old London Timeless Sand Floor Standing 2 Door Vanity Basin Unit with Square Basin & 1 Tap Hole Marble Top, 600mm - Timeless Sand
87038 Old London Floor Standing 2 Door Vanity Unit with 1 Tap Hole Grey Marble Top 600mm - Timeless Sand
87039 Old London Floor Standing 2 Door Vanity Unit with 3 Tap Hole Black Marble Top 600mm - Timeless Sand
87040 Old London Floor Standing 2 Door Vanity Unit with 3 Tap Hole White Marble Top 600mm - Timeless Sand
87041 Old London Floor Standing 2 Door Vanity Unit with 3 Tap Hole Grey Marble Top 600mm - Timeless Sand
87093 Old London Floor Standing 3 Door Vanity Unit with 1 Tap Hole Black Marble Top 600mm - Hunter Green
87094 Old London Floor Standing 3 Door Vanity Unit with 1 Tap Hole White Marble Top 600mm - Hunter Green
87095 Old London Old London Hunter Green Floor Standing 4 Door Vanity Basin Unit with Square Basin & 1 Tap Hole Marble Top, 1200mm - Hunter Green
87101 Old London Floor Standing 3 Door Vanity Unit with 1 Tap Hole White Marble Top 800mm - Hunter Green
87102 Old London Old London Hunter Green Floor Standing 2 Door Vanity Basin Unit with Square Basin & 1 Tap Hole Marble Top, 600mm - Hunter Green
87103 Old London Floor Standing 3 Door Vanity Unit with 1 Tap Hole Grey Marble Top 800mm - Hunter Green
87104 Old London Floor Standing 3 Door Vanity Unit with 3 Tap Hole Black Marble Top 800mm - Hunter Green
87105 Old London Floor Standing 3 Door Vanity Unit with 3 Tap Hole White Marble Top 800mm - Hunter Green
87106 Old London Floor Standing 3 Door Vanity Unit with 3 Tap Hole Grey Marble Top 800mm - Hunter Green