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 (
    19981, 19982, 19983, 19984, 19985, 19986, 
    19987, 19988, 19989, 19990, 19991, 
    19992, 19993, 19994, 19995, 19996
  ) 
  AND cscart_product_descriptions.lang_code = 'en'

Query time 0.00032

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 (19981,19982,19983,19984,19985,19986,19987,19988,19989,19990,19991,19992,19993,19994,19995,19996) and cscart_product_descriptions.lang_code = 'en'"
    }
  }
}

Result

product_id short_description full_description unit_name
19981 G sensor assembly - front wheel, left<p>Part number 54695T6050</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
19982 G sensor assembly - front wheel, right<p>Part number 54696T6050</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
19983 insulator assembly<p>Part number 55310T6050</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
19984 Pad-rear spring, lower part<p>Part number 55333T6000</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
19985 Pad-rear spring, upper<p>Part number 55334T6000</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
19986 Shock Absorber Assembly - Rear<p>Part number 55307T6351</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
19987 Bar Assembly - Rear Stabilizer<p>Part number 55510T6000</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
19988 Arm complete - rear lower, right<p>Part number 55211T6000</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
19989 Arm complete - rear lower, left<p>Part number 55210T6000</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
19990 Arm assembly-rear upper, right<p>Part number 55121T6000</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
19991 Arm Assembly - Rear Assist<p>Part number 55250T6000</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
19992 Link Assembly - Rear Stabilizer<p>Part number 55530T6000</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
19993 Arm assembly-rear upper, left<p>Part number 55120T6000</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
19994 Arm Complete-Rear Upper Rear<p>Part number 55130T6000</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
19995 Wheel Assembly - Steering<p>Part number 56100T6830SR3</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
19996 Cover assembly - lower steering wheel<p>Part number 56120T6000DUE</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>