Probably breaking out of the subrutines is the best solution. However I am not an expert in this. You could solve it delaying a little bit the search operations, so to say "waiting" to see if the user is typing the next character or not. For example:

$EntryQuery->bind("<Key>", sub {
    if ($Timer){$Timer->cancel();}
    $Timer = $EntryQuery->after(100, sub {
        my $ResultsFinal=Query($QueryInput);
        DeleteAllRowsInTable();
        PrintingResultsInTable($ResultsFinal);
    });
}
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Monks with more experience may tell you if this is a reasonable approach.