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 (
    21775, 21776, 21777, 21778, 21779, 21780, 
    21781, 21782, 21783, 21784, 21785, 
    21786, 21787, 21788, 21789, 21790
  ) 
  AND cscart_product_descriptions.lang_code = 'ru'

Query time 0.00065

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 (21775,21776,21777,21778,21779,21780,21781,21782,21783,21784,21785,21786,21787,21788,21789,21790) and cscart_product_descriptions.lang_code = 'ru'"
    }
  }
}

Result

product_id short_description full_description unit_name
21775 Nozzle assembly - side defroster, right<p>Part number 97393T1000NBD</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
21776 Hose-side defroster left<p>Part number 97381T1000</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
21777 Hose-side defroster right side<p>Part number 97391T1000</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
21778 Glass-windshield<p>Part number 86111JI020</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
21779 Coupler-Front View Camera<p>Part number 99216JI000</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
21780 Actuator - Active Air<p>Part number 86969T1000</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
21781 Flap & Duct Assemblies - Active Air<p>Part number 86950T1000</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
21782 Holder-Parking Assist System NO.1<p>Part number 86581T1000</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
21783 Tapping Screw Assy - License Plate Mounting<p>Part number 86912B1000</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
21784 Wiring Harness - Front Bumper<p>Part number 91890T1170</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
21785 Ultrasonic Sensor Assembly-Parking Assist System<p>Part number 99350T1000URA</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
21786 Bolt-Rear License Plate<p>Part number 86911B1000</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
21787 Ultrasonic Sensor Assembly-Parking Assist System<p>Part number 99310L1000URA</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
21788 Ultrasonic Sensor Assembly-Parking Assist System<p>Part number 99310L1200URA</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
21789 Molding Subassembly - Back Panel<p>Part number 87380T1000URA</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
21790 Mirror assembly - outside rear view, left<p>Part number 87610JI010URA</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>