You say you only want the one which is closest. So instead of using spacec saving data you don't need, and undergoing the expense of a sort, why not keep track of the closest as you go along. It's much the same as determining the minimum of a list.

$delta = time();      // has to be less than now - 1970
$minval = $min;
for ( @returns ) {
    my $val = abs( $ctime - $_ );
    if ( $val < $delta ) {
        $delta = $val;
        $minval = $_;
    }
}
print "MULTIPLE MATCH best match = $minval";
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update: I see I'll have to learn to type faster!

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