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 (
    20189, 20190, 20191, 20192, 20193, 20194, 
    20195, 20196, 20197, 20198, 20199, 
    20200, 20201, 20202, 20203, 20204
  ) 
  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 (20189,20190,20191,20192,20193,20194,20195,20196,20197,20198,20199,20200,20201,20202,20203,20204) and cscart_product_descriptions.lang_code = 'en'"
    }
  }
}

Result

product_id short_description full_description unit_name
20189 Carrier Assembly - Front End Module<p>Part number 64101T6000</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
20190 Panel Assy-Cowl & Dash Complete<p>Part number 64200T6000</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
20191 Member Assembly - Dash Cross Complete<p>Part number 64350T6000</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
20192 Bulkhead-side sill inner front, left<p>Part number 644C2T6000</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
20193 Bulkhead-side sill inner front, right<p>Part number 644D2T6000</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
20194 Panel complete - fender apron, left<p>Part number 64500T6000</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
20195 Panel complete - fender apron, right<p>Part number 64600T6000</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
20196 Beam Complete - Front Bumper<p>Part number 64900T6000</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
20197 Insulator-dash panel<p>Part number 84124T6000</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
20198 Panel assembly - floor, center<p>Part number 65100T6000</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
20199 Reinforcement Assembly - Center Floor<p>Part number 65130T6000</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
20200 Panel assembly - side seal inner, left<p>Part number 65171T6000</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
20201 Panel assembly - side sill inner, right<p>Part number 65181T6000</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
20202 Member Assembly - Center Floor Complete<p>Part number 65200T6000</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
20203 Bracket - rear door scuff mounting, right<p>Part number 655K9T6000</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
20204 Rainf - Rear floor side, left<p>Part number 65436T6000</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>