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 (
    85974, 85975, 85977, 85978, 85979, 85980, 
    85981, 85982, 85983, 85984, 85985, 
    85986, 85987, 85988, 85989, 85990, 
    85991, 85992, 85993, 85994, 85995, 
    85996, 85997, 85998, 85999, 86003, 
    86004, 86005, 86006, 86007, 86008, 
    86009, 86010, 86011, 86012, 86014, 
    86015, 86017, 86018, 86019, 86020, 
    86021, 86022, 86023, 86024, 86025, 
    86026, 86027
  ) 
  AND cscart_product_descriptions.lang_code = 'en'

Query time 0.00113

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "21.63"
    },
    "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": 48,
      "rows_produced_per_join": 48,
      "filtered": "100.00",
      "cost_info": {
        "read_cost": "16.83",
        "eval_cost": "4.80",
        "prefix_cost": "21.63",
        "data_read_per_join": "183K"
      },
      "used_columns": [
        "product_id",
        "lang_code",
        "short_description",
        "full_description"
      ],
      "attached_condition": "((`nuie_scalesta_net`.`cscart_product_descriptions`.`product_id` in (85974,85975,85977,85978,85979,85980,85981,85982,85983,85984,85985,85986,85987,85988,85989,85990,85991,85992,85993,85994,85995,85996,85997,85998,85999,86003,86004,86005,86006,86007,86008,86009,86010,86011,86012,86014,86015,86017,86018,86019,86020,86021,86022,86023,86024,86025,86026,86027)) and (`nuie_scalesta_net`.`cscart_product_descriptions`.`lang_code` = 'en'))"
    }
  }
}

Result

product_id short_description full_description
85974 nuie Handles Bar Handle 96mm Centres - Chrome
85975 nuie Handles D Handle 96mm Centres - Chrome
85977 Hudson Reed Handles D Handle 128mm Centres - Chrome
85978 nuie Handles D Handle 320mm Centres - Chrome
85979 nuie Handles Handle 420mm Centres - Chrome
85980 Hudson Reed Profile Handle 352mm Centres - Chrome Black
85981 nuie Handles Seven Shaped Handle 480mm Centres - Chrome
85982 nuie Handles Knurled Bar Handle 96mm Centres - Chrome
85983 nuie Handles Knurled Bar Handle 160mm Centres - Chrome
85984 nuie Handles Knurled Bar Handle 192mm Centres - Chrome
85985 nuie Handles D Handle 192mm Centres - Chrome
85986 nuie Handles D Handle 192mm Centres - Brushed Brass
85987 nuie Handles D Handle 192mm Centres - Matt Black
85988 nuie Handles D Handle 192mm Centres - Copper
85989 nuie Handles Knurled Bar Handle 96mm Centres - Matt Black
85990 nuie Handles Knurled Bar Handle 160mm Centres - Matt Black
85991 nuie Handles Knurled Bar Handle 192mm Centres - Matt Black
85992 nuie Handles D Handle 160mm Centres - Chrome
85993 nuie Handles D Handle 160mm Centres - Brushed Brass
85994 nuie Handles D Handle 160mm Centres - Matt Black
85995 nuie Handles D Handle 160mm Centres - Copper
85996 nuie Handles Knurled Bar Handle 96mm Centres - Brushed Brass
85997 nuie Handles Knurled Bar Handle 160mm Centres - Brushed Brass
85998 nuie Handles Knurled Bar Handle 192mm Centres - Brushed Brass
85999 Hudson Reed D Shaped Handle 256mm Centres - Chrome
86003 nuie Handles Profile Handle 160mm Centres - Chrome
86004 nuie Handles Profile Handle 224mm Centres - Chrome
86005 nuie Handles D Shaped Handle 160mm Centres - Chrome
86006 nuie Handles D Shaped Handle 224mm Centres - Chrome
86007 nuie Handles D Shaped Handle 160mm Centres - Chrome
86008 nuie Handles D Shaped Handle 224mm Centres - Chrome
86009 nuie Handles Profile Handle 160mm Centres - Chrome
86010 nuie Handles Profile Handle 224mm Centres - Chrome
86011 nuie Handles Finger Pull Handle 160mm Centres - Chrome
86012 nuie Handles Finger Pull Handle 224mm Centres - Chrome
86014 nuie Handles Square Drop Handle 32mm Centres - Chrome
86015 nuie Handles Indented Round Knob - Chrome
86017 nuie Handles 328mm D Handle Chrome - Chrome
86018 nuie Handles Square Strap Chrome Handle 128mm Centres - Chrome
86019 nuie Handles Finger Pull Handle 150mm - Chrome
86020 nuie Handles Finger Pull Handle 300mm - Chrome
86021 nuie Handles Finger Pull Handle 500mm - Chrome
86022 nuie Handles Round Strap Chrome Handle 128mm Centres - Chrome
86023 nuie Handles Art Deco Chrome Handle 160mm Centres - Chrome
86024 nuie Handles D Handle 150mm Centres - Chrome
86025 nuie Handles Slim Line D Handle 150mm Centres - Chrome
86026 Hudson Reed Handles Strap Handle 96mm Centres - Chrome
86027 Hudson Reed Handles D Handle 192mm Centres - Chrome