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 (
    20221, 20222, 20223, 20224, 20225, 20226, 
    20227, 20228, 20229, 20230, 20231, 
    20232, 20233, 20234, 20235, 20236
  ) 
  AND cscart_product_descriptions.lang_code = 'ru'

Query time 0.00071

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 (20221,20222,20223,20224,20225,20226,20227,20228,20229,20230,20231,20232,20233,20234,20235,20236) and cscart_product_descriptions.lang_code = 'ru'"
    }
  }
}

Result

product_id short_description full_description unit_name
20221 Insulator-fender right side<p>Part number 84126T6000</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
20222 Insulator-fender top, left<p>Part number 841E6T6000</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
20223 Insulator-fender inner upper, left<p>Part number 841E9T6000</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
20224 Insulator - top of fender, right<p>Part number 841F6T6000</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
20225 Insulator-fender inner upper, right<p>Part number 841F9T6000</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
20226 Panel assembly-pillar outer, left<p>Part number 71110T6A00</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
20227 Panel assembly-pillar outer, right<p>Part number 71120T6A00</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
20228 Pillar assembly-front inner, left<p>Part number 71201T6000</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
20229 Pillar assembly-front inner, right<p>Part number 71202T6000</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
20230 Panel-side sill outer, left<p>Part number 71312T6D00</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
20231 Panel-side sill outer, right<p>Part number 71322T6D00</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
20232 Pillar assembly - center inner, left<p>Part number 71401T6050</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
20233 Pillar assembly - center inner, right<p>Part number 71402T6050</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
20234 Panel assembly - quarter outer, left<p>Part number 71503T6C00</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
20235 Panel assembly - quarter outer, right<p>Part number 71504T6C00</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
20236 Panel assembly - quarter inner, left<p>Part number 71601T6050</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>