Try to change the sql query a bit:
declare @inStock uniqueidentifier
set @inStock = '1C139F6C-F210-4002-90D0-4DFAF98D5FA4'
declare @assetStatus uniqueidentifier
set @assetStatus = '3028166F-C0D6-41D8-9CB7-F64852E0FD01'
declare @hoursAfterLogon int
set @hoursAfterLogon = 5 -- five hours after logged on
select distinct
_ResourceGuid AS GUID
from
Evt_AeX_Client_LogOn ac
join ResourceAssociation ra on ac._ResourceGuid = ra.ParentResourceGuid
where
ra.ResourceAssociationTypeGuid = @assetStatus and ra.ChildResourceGuid = @inStock
and datediff(hh, ac._eventTime, getdate()) < @hoursAfterLogon