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 (
    18589, 18590, 18591, 18592, 18593, 18594, 
    18595, 18596, 18597, 18598, 18599, 
    18600, 18601, 18602, 18603, 18604
  ) 
  AND cscart_product_descriptions.lang_code = 'ru'

Query time 0.00044

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 (18589,18590,18591,18592,18593,18594,18595,18596,18597,18598,18599,18600,18601,18602,18603,18604) and cscart_product_descriptions.lang_code = 'ru'"
    }
  }
}

Result

product_id short_description full_description unit_name
18589 Garnish assy-console, left<p>Part number 84690G9AC0DUE</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
18590 Garnish Assy-Console, Right<p>Part number 84695G9AA0DUE</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
18591 Clip-Trim Mounting<p>Part number 847473Y000</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
18592 Wiring Harness-Extension<p>Part number 91875G9070</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
18593 Complete-Console Follower Switch<p>Part number 93300G9BB0</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
18594 Socket Assembly-Accessories<p>Part number 95120G9AA04X</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
18595 Antenna Assembly-Smart Key<p>Part number 95460G9000</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
18596 Unit Assembly - Wireless Charging<p>Part number 95560G97104X</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
18597 Indicator - Wireless Charging<p>Part number 95580G9700</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
18598 Charger Assembly-USB<p>Part number 96125CU000NNB</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
18599 Charger Assembly-USB<p>Part number 96125G9BB04X</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
18600 Bracket-USB Charger Assembly<p>Part number 846G1G9000</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
18601 Duct assembly-rear air ventilator, NO.3<p>Part number 97030G9010</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
18602 Duct Assembly-Rear Air Ventilator, NO.4<p>Part number 97040G9AA04X</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
18603 Bar Assembly - Cowl Cross<p>Part number 84410G9200</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
18604 Housing Assembly - Glove Box<p>Part number 84510G9AA0DUE</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>