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 (
    10418, 10419, 10420, 10421, 10434, 10436, 
    10450, 10453, 10459, 10466, 10470, 
    10471, 10472, 10473, 10477, 10478
  ) 
  AND cscart_product_descriptions.lang_code = 'en'

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 (10418,10419,10420,10421,10434,10436,10450,10453,10459,10466,10470,10471,10472,10473,10477,10478) and cscart_product_descriptions.lang_code = 'en'"
    }
  }
}

Result

product_id short_description full_description unit_name
10418 Hook-to-ing<p>Part number 091471H000</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
10419 Bolt (Washer)<p>Part number 1125406203</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
10420 screw-tapping<p>Part number 1243305123</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
10421 Sealant - Tire<p>Part number 52932A9700</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
10434 Clip-Trim Mounting<p>Part number 858492E000</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
10436 coil spring<p>Part number 858393K000</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
10450 screw-tapping<p>Part number 1249204127K</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
10453 Glass-windshield<p>Part number 86111JI160</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
10459 Weather Strip-Hood<p>Part number 86430T1000</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
10466 Sensor-Auto Defog<p>Part number 97257S1000</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
10470 screw-tapping<p>Part number 1249205169B</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
10471 End piece, left<p>Part number 86547T1000</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
10472 End piece, right<p>Part number 86548T1000</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
10473 nut-speed<p>Part number 0K2A150044</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
10477 Cover - Front Bumper<p>Part number 86550T1010</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
10478 Grille-Front Bumper<p>Part number 86530T1100</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>