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 (
    20557, 20558, 20559, 20560, 20561, 20562, 
    20563, 20564, 20565, 20566, 20567, 
    20568, 20569, 20570, 20571, 20572
  ) 
  AND cscart_product_descriptions.lang_code = 'ru'

Query time 0.00035

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 (20557,20558,20559,20560,20561,20562,20563,20564,20565,20566,20567,20568,20569,20570,20571,20572) and cscart_product_descriptions.lang_code = 'ru'"
    }
  }
}

Result

product_id short_description full_description unit_name
20557 Panel assembly - fuel filler door<p>Part number 69511T1000</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
20558 Deflector Assembly-Panorama Roof<p>Part number 81690T1000</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
20559 Center Device - Panoramic Roof<p>Part number 816893R500</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
20560 Motor assembly - panoramic roof (glass)<p>Part number 81680T1000</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
20561 Motor assembly - panoramic roof (roller)<p>Part number 81679T1000</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
20562 Carriage Assembly-Right<p>Part number 81654T1000</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
20563 front frame assembly<p>Part number 81660T1000</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
20564 Mechanism rail assembly, left<p>Part number 81651T1000</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
20565 Mechanism rail assembly, right<p>Part number 81652T1000</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
20566 Tapping screw-washer assembly<p>Part number 82290T4000</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
20567 Garnish assembly-door frame, left<p>Part number 82250T1000</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
20568 Garnish assembly-door frame, right<p>Part number 82260T1000</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
20569 Panel assembly - front door trim, right<p>Part number 82306T1550NDF</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
20570 Panel assembly - front door trim, left<p>Part number 82305T1550NDF</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
20571 Handle assembly - door inside, left<p>Part number 82610T1000VCS</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
20572 Handle assembly - door inside, right<p>Part number 82620T1000VCS</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>