N1QL DELETE query taking time to execute after indexing also

Couchbase Server
1

CREATE INDEX ix1c_UserAsset ON content(createdAt DESC,type,_type,status, name,tags,url,_id) WHERE _type=“UserAsset”

for UserAsset model above one is the Index which I have created. All the select query are working fine instead of one delete query mentioned below.

DELETE FROM content
WHERE _type=“UserAsset” AND _id=“887a35e9-81cc-40b3-bb0d-657a64caed81”

It’s taking arround 20sec to execute,where as it should be executed with in a seconds. Please suggest if any modification required in the Query or Index.

2 
CREATE INDEX ix1d_UserAsset ON content(_id) 
WHERE _type="UserAsset";