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 (
    21903, 21904, 21905, 21906, 21907, 21908, 
    21909, 21910, 21911, 21912, 21913, 
    21914, 21915, 21916, 21917, 21918
  ) 
  AND cscart_product_descriptions.lang_code = 'ru'

Query time 0.01018

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 (21903,21904,21905,21906,21907,21908,21909,21910,21911,21912,21913,21914,21915,21916,21917,21918) and cscart_product_descriptions.lang_code = 'ru'"
    }
  }
}

Result

product_id short_description full_description unit_name
21903 Hose Assembly - Water Outlet<p>Part number 97312T1000</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
21904 compressor assembly<p>Part number 97701T1000</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
21905 Hose-Discharge<p>Part number 97762T1000</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
21906 Tube Assemblies - Suction & Liquid<p>Part number 97775T1000</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
21907 hose-suction<p>Part number 97763T1000</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
21908 Engine Assembly-Sub<p>Part number 176G13NA01</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
21909 Engine Assembly - Short<p>Part number 253G23NA01</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
21910 insert<p>Part number 211713N100</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
21911 Block Serve Assy-Cylinder<p>Part number 211103N600</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
21912 Block Serve Assy-Cylinder<p>Part number 351G33NA01</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
21913 Rod assembly - oil level gauge<p>Part number 266113N200</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
21914 Guide-Oil Level Gauge<p>Part number 266123N200</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
21915 damper<p>Part number 21823T6250</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
21916 Bracket Assembly - Transmission Mounting<p>Part number 21730T6450</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
21917 Bracket assembly - engine mounting, right<p>Part number 21840T6200</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
21918 Bracket - engine support, left<p>Part number 21826T6250</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>