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 (
    20845, 20846, 20847, 20848, 20849, 20850, 
    20851, 20852, 20853, 20854, 20855, 
    20856, 20857, 20858, 20859, 20860
  ) 
  AND cscart_product_descriptions.lang_code = 'ru'

Query time 0.01107

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 (20845,20846,20847,20848,20849,20850,20851,20852,20853,20854,20855,20856,20857,20858,20859,20860) and cscart_product_descriptions.lang_code = 'ru'"
    }
  }
}

Result

product_id short_description full_description unit_name
20845 SAB module assembly-rear, right<p>Part number 80640T1000</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
20846 Bolt-Washer Assembly<p>Part number 1124106141</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
20847 Wiring harness-rear seat, right<p>Part number 89661T1610</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
20848 Bezel assembly-rear seat armrest<p>Part number 89917T1520RWD</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
20849 Cup holder assembly - rear seat armrest<p>Part number 89903T1040OWN</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
20850 Guide assembly - center headrest, left<p>Part number 89380B1000OWN</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
20851 Headrest Assembly-Rear Seat Center<p>Part number 89705T1300JK6</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
20852 Guide assembly - center headrest, right<p>Part number 89480B1000OWN</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
20853 Armrest Assembly-Rear Seat Bag<p>Part number 89900T1JB1JK6</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
20854 Wiring harness-rear seat, left<p>Part number 89561T1610</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
20855 SAB module assembly-rear, left<p>Part number 80630T1000</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
20856 CCS ECU assembly<p>Part number 89B81T1500</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
20857 Ventilation assembly-rear back, right<p>Part number 894P7T1500</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
20858 Grille assembly-rear back, right<p>Part number 89902D2500</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
20859 Ventilation assembly-rear back, left<p>Part number 893P7T1500</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
20860 CCS (ventilation) ECU unit - rear<p>Part number 89B80T1500</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>