200>/var/lock/mylockfile
is, in this context, information about how the subshell should be configured (how its redirection is supposed to be set up). It's not a separate command.
This is true in the same way that
echo "foo" >bar.txt
...always does the redirection first, as does
>bar.txt echo "foo"
In neither of these cases does order matter at all.
A subshell is similar in this respect -- it's just a compound command, and like any other command, it can have redirections specified either at its beginning or its end.