Yes, this is possible, but the default RX1 window is 1 sec.
See also the following
# Get downlink data delay.
# This is the time that LoRa Server waits between forwarding data to the
# application-server and reading data from the queue. A higher value
# means that the application-server has more time to schedule a downlink
# queue item which can be processed within the same uplink / downlink
# Please note that this value has influence on the uplink / downlink
# roundtrip time. Setting this value too high means LoRa Server will be
# unable to respond to the device within its receive-window.