Proper Indexing For ORDER BY

SQL++
1

Hi,

I have created the below INDEX
CREATE INDEX assets ON assets(status,type,created_on DESC)
For the following DOCUMENT

{
  "created_on": 1507299722,
  "modified_on": 1507299722,
  "eloc": "TTBT76",
  "type": "atlas",
  "source": 101,
  "asset_name": "43b174f6cbc818fb.jpg",
  "user_id": "38c345d166882c68d7029bb0960752c5",
  "status": 1,
  "pin_id": "4c032de3989b4b20015d3f109118518b"
}

When I run SELECT asset_name,created_on, eloc FROM assets WHERE status=0 AND type=‘review’ ORDER BY created_on DESC LIMIT 10;
The query takes 10ms which I expect from the query but when I run SELECT asset_name,created_on, eloc FROM assets WHERE status IS NOT MISSING AND type IS NOT MISSING ORDER BY created_on DESC LIMIT 10;
The query takes more than 2 seconds. Am I missing something and what is the correct way to achieve a faster result?
I always follow https://blog.couchbase.com/create-right-index-get-right-performance/ article for creating INDEXES.