There are two ways to accomplish this. First (and preferred) way is to run a dummy query:
<cfquery name="unlock" datasource="users">
select money from nothing
</cfquery>
Second way is to use an undocumented Coldfusion function:
<cfset null = cfusion_dbconnections_flush()>
Mind you this will flush all your database connections, so unless you really need to I would just stick with the first method.