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 (
    19949, 19950, 19951, 19952, 19953, 19954, 
    19955, 19956, 19957, 19958, 19959, 
    19960, 19961, 19962, 19963, 19964
  ) 
  AND cscart_product_descriptions.lang_code = 'en'

Query time 0.00036

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 (19949,19950,19951,19952,19953,19954,19955,19956,19957,19958,19959,19960,19961,19962,19963,19964) and cscart_product_descriptions.lang_code = 'en'"
    }
  }
}

Result

product_id short_description full_description unit_name
19949 Clutch Assembly-6<p>Part number 454104J300</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
19950 Clutch assembly-underdrive<p>Part number 455104J300</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
19951 Hub-underdrive clutch<p>Part number 455894J300</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
19952 Hub-4 & O/D Clutch<p>Part number 455774J300</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
19953 Shaft Assembly - Input<p>Part number 457014J600</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
19954 Carrier Assembly - Front Planet<p>Part number 457204J700</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
19955 Carrier Assembly - Middle Planet<p>Part number 457504J610</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
19956 Carrier assembly - rear planet<p>Part number 457804J600</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
19957 Shaft Assembly-Output<p>Part number 458164J000</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
19958 Disc-front wheel brake<p>Part number 51712T6200</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
19959 Knuckle-front axle, left<p>Part number 51710T6500</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
19960 Knuckle-front axle, right<p>Part number 51711T6500</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
19961 ball joint assembly<p>Part number 51760T6000</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
19962 Hub & Bearing Assembly-Rear<p>Part number 52730T6000</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
19963 Carrier assembly - rear axle, left<p>Part number 52710T6000</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
19964 Carrier assembly - rear axle, right<p>Part number 52711T6000</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>