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 (
    20541, 20542, 20543, 20544, 20545, 20546, 
    20547, 20548, 20549, 20550, 20551, 
    20552, 20553, 20554, 20555, 20556
  ) 
  AND cscart_product_descriptions.lang_code = 'ru'

Query time 0.00939

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 (20541,20542,20543,20544,20545,20546,20547,20548,20549,20550,20551,20552,20553,20554,20555,20556) and cscart_product_descriptions.lang_code = 'ru'"
    }
  }
}

Result

product_id short_description full_description unit_name
20541 Trim assembly - center pillar lower, right<p>Part number 85845T6500UBL</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
20542 Trim Assembly - Rear Pillar Left<p>Part number 85850T6700DUE</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
20543 Trim assembly - rear pillar, right<p>Part number 85860T6700DUE</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
20544 Trim Assembly - Front Door Scuff Left<p>Part number 85870T6000UBL</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
20545 Trim - front step plate, left<p>Part number 85873T6000UBL</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
20546 Trim - front step plate, right<p>Part number 85883T6000UBL</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
20547 Trim assembly - rear door scuff, left<p>Part number 85875T6000UBL</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
20548 Trim assembly - rear door scuff, right<p>Part number 85885T6000UBL</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
20549 Trim - rear step plate left<p>Part number 85877T6000UBL</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
20550 Trim - rear step plate right<p>Part number 85887T6000UBL</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
20551 Nozzle assembly - side defroster, left<p>Part number 97383T6000DUE</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
20552 Nozzle assembly - side defroster, right<p>Part number 97393T6000DUE</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
20553 Hose-side defroster left<p>Part number 97381T6000</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
20554 Hose-side defroster right side<p>Part number 97391T6000</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
20555 Opener Assembly - Fuel Filler Door<p>Part number 81560T1000</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
20556 Housing - Fuel Filler Door<p>Part number 81595T1000</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>