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 (
    87907, 87940, 88091, 88090, 88087, 88086, 
    94451, 94798, 94799, 94800, 94801, 
    94823, 94824, 94827, 94828, 94829, 
    94830, 94831, 95736, 95743, 95744, 
    95745, 95746, 95747, 95748, 95749, 
    95750, 95751, 95752, 95813
  ) 
  AND cscart_product_descriptions.lang_code = 'en'

Query time 0.00072

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 (87907,87940,88091,88090,88087,88086,94451,94798,94799,94800,94801,94823,94824,94827,94828,94829,94830,94831,95736,95743,95744,95745,95746,95747,95748,95749,95750,95751,95752,95813)) and (`nuie_scalesta_net`.`cscart_product_descriptions`.`lang_code` = 'en'))"
    }
  }
}

Result

product_id short_description full_description
87907 nuie Round Vessel 358 x 368 x 137mm
87940 Old London Chancery 500mm Basin 1 Tap Hole
88086 nuie Melbourne 350mm Wall Hung Basin
88087 nuie Melbourne 450mm Wall Hung Basin
88090 nuie Melbourne 350mm Wall Hung Basin
88091 nuie Melbourne 450mm Wall Hung Basin
94451
94798
94799
94800
94801
94823
94824
94827
94828
94829
94830
94831
95736
95743
95744
95745
95746
95747
95748
95749
95750
95751
95752
95813