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, 
  cscart_product_descriptions.unit_name 
FROM 
  cscart_product_descriptions 
WHERE 
  cscart_product_descriptions.product_id IN (
    20797, 20798, 20799, 20800, 20801, 20802, 
    20803, 20804, 20805, 20806, 20807, 
    20808, 20809, 20810, 20811, 20812
  ) 
  AND cscart_product_descriptions.lang_code = 'ru'

Query time 0.01021

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "table_name": "cscart_product_descriptions",
      "access_type": "range",
      "possible_keys": ["PRIMARY", "product_id", "idx_product_lang"],
      "key": "PRIMARY",
      "key_length": "9",
      "used_key_parts": ["product_id", "lang_code"],
      "rows": 16,
      "filtered": 100,
      "index_condition": "cscart_product_descriptions.product_id in (20797,20798,20799,20800,20801,20802,20803,20804,20805,20806,20807,20808,20809,20810,20811,20812) and cscart_product_descriptions.lang_code = 'ru'"
    }
  }
}

Result

product_id short_description full_description unit_name
20797 Bolt-Rear License Plate<p>Part number 86699A7200</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
20798 Lamp assembly - back up, left<p>Part number 924A3T1100</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
20799 Lamp assembly - back up, right<p>Part number 924A4T1100</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
20800 Antenna Assembly-Smart Key<p>Part number 95460L1000</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
20801 Cover Assembly - Spare Tire<p>Part number 86880T1000</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
20802 Guard assembly - front wheel, left<p>Part number 86811T1000</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
20803 Guard assembly - front wheel, right<p>Part number 86812T1000</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
20804 Guard-rear wheel, left<p>Part number 86821T1000</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
20805 Guard-rear wheel, right<p>Part number 86822T1000</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
20806 Cover assembly-under, center<p>Part number 87150T10004X</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
20807 Glass assembly - rear window<p>Part number 87110T1000</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
20808 Tapping screw - flange head<p>Part number 1249204087E</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
20809 Emblem-GENESIS<p>Part number 86311T1100</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
20810 Molding-back panel, upper part (CR)<p>Part number 87373T1000</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
20811 Pad-Trunk Lid Garnish<p>Part number 87368T1000</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
20812 Strip-Back Panel Molding<p>Part number 87374T1000</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>