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 (
    82071, 82118, 82073, 82038, 149042, 
    82061, 81948, 82101, 82009, 81647, 
    82133, 82103, 81737, 81655, 82104, 
    81704, 81826, 81863, 81741, 81860, 
    81702, 82072, 81634, 81657, 81739, 
    81625, 82115, 81776, 82074, 81862, 
    81627, 82114, 82069, 81773, 81636, 
    81624, 82099, 82052, 82096, 81747, 
    82116, 82095
  ) 
  AND cscart_product_descriptions.lang_code = 'en'

Query time 0.00206

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "58.88"
    },
    "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": 42,
      "rows_produced_per_join": 42,
      "filtered": "100.00",
      "cost_info": {
        "read_cost": "50.48",
        "eval_cost": "8.40",
        "prefix_cost": "58.88",
        "data_read_per_join": "286K"
      },
      "used_columns": [
        "product_id",
        "lang_code",
        "short_description",
        "full_description"
      ],
      "attached_condition": "((`webmarco`.`cscart_product_descriptions`.`product_id` in (82071,82118,82073,82038,149042,82061,81948,82101,82009,81647,82133,82103,81737,81655,82104,81704,81826,81863,81741,81860,81702,82072,81634,81657,81739,81625,82115,81776,82074,81862,81627,82114,82069,81773,81636,81624,82099,82052,82096,81747,82116,82095)) and (`webmarco`.`cscart_product_descriptions`.`lang_code` = 'en'))"
    }
  }
}