How to fetch data from dynamodb with Keycondition expression with sort key timestamp?

i am facing some issue with querying data from DynamoDB can any one of you help me on this and i am coding in NodeJS.

My table looks like below with,

Primary key: RequestId
Secondary index: Userid with sortkey Timestamp

when i am pulling the data using UserId, I am getting lot's for records so, planning to pull the data with Timestamp condition.

RequestId Request Timestamp UserId

via abhishek