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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 (
    86031, 86032, 86033, 86034, 86035, 86036, 
    86037, 86038, 86039, 86040, 86041, 
    86042, 86043, 86044, 86045, 86046, 
    86047, 86048, 86049, 86050, 86051, 
    86052, 86053, 86054, 86055, 86056, 
    86057, 86058, 86059, 86060
  ) 
  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 (86031,86032,86033,86034,86035,86036,86037,86038,86039,86040,86041,86042,86043,86044,86045,86046,86047,86048,86049,86050,86051,86052,86053,86054,86055,86056,86057,86058,86059,86060)) and (`nuie_scalesta_net`.`cscart_product_descriptions`.`lang_code` = 'en'))"
    }
  }
}

Result

product_id	short_description	full_description
86031	nuie Handles Slim Line D Handle 150mm Centres - Matt Black
86032	nuie Handles D Shape Bar Handle 210mm Centres - Matt Black
86033	nuie Handles D Shape Bar Handle 210mm Centres - Brushed Brass
86034	nuie Handles Bar Handle 155mm Centres - Matt Black
86035	nuie Handles Bar Handle 155mm Centres - Brushed Brass
86036	nuie Handles Wrap Over Handle 50mm Centres - Brushed Brass
86037	nuie Handles D Handle 150mm Centres - Brushed Brass
86038	nuie Handles Slim Line D Handle 150mm Centres - Brushed Brass
86039	nuie Handles D Shape Bar Handle 210mm Centres - Chrome
86040	nuie Handles Profile Handle 160mm Centres - Matt Black
86041	nuie Handles Profile Handle 224mm Centres - Matt Black
86042	nuie Handles D Shaped Handle 160mm Centres - Matt Black
86043	nuie Handles D Shaped Handle 224mm Centres - Matt Black
86044	nuie Handles D Shaped Handle 160mm Centres - Matt Black
86045	nuie Handles D Shaped Handle 224mm Centres - Matt Black
86046	nuie Handles Profile Handle 160mm Centres - Matt Black
86047	nuie Handles Profile Handle 224mm Centres - Matt Black
86048	nuie Handles Finger Pull Handle 160mm Centres - Matt Black
86049	nuie Handles Finger Pull Handle 224mm Centres - Matt Black
86050	nuie Handles Square Drop Handle 32mm Centres - Matt Black
86051	nuie Handles Indented Round Knob - Matt Black
86052	nuie Handles Knurled Round Knob - Matt Black
86053	nuie Handles 328mm D Handle Matt Black - Matt Black
86054	nuie Handles Finger Pull Handle 150mm - Matt Black
86055	nuie Handles Finger Pull Handle 300mm - Matt Black
86056	nuie Handles Finger Pull Handle 500mm - Matt Black
86057	nuie Handles Chrome Strap Handle 128mm Centres - Chrome
86058	nuie Handles Square Drop Handle 32mm Centres - Brushed Brass
86059	nuie Handles Indented Round Knob - Brushed Brass
86060	nuie Handles Knurled Round Knob - Brushed Brass