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 (
    100858, 100859, 100860, 100861, 100862, 
    100867, 100868, 100869, 100870, 100877, 
    100878, 101055, 101056, 101057, 101058, 
    101059, 101060, 101061, 101062, 101063, 
    101064, 101065, 101066, 101067, 101068, 
    101069, 101070, 101071, 101072, 101073, 
    101074, 101075, 101076, 101077, 101078, 
    101079, 101080, 101081, 101082, 101083, 
    101084, 101085, 101086, 101087, 101088, 
    101089, 101090, 101091
  ) 
  AND cscart_product_descriptions.lang_code = 'en'

Query time 0.00106

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 (100858,100859,100860,100861,100862,100867,100868,100869,100870,100877,100878,101055,101056,101057,101058,101059,101060,101061,101062,101063,101064,101065,101066,101067,101068,101069,101070,101071,101072,101073,101074,101075,101076,101077,101078,101079,101080,101081,101082,101083,101084,101085,101086,101087,101088,101089,101090,101091)) and (`nuie_scalesta_net`.`cscart_product_descriptions`.`lang_code` = 'en'))"
    }
  }
}