A faster way:

my @array = qw(name John number 7 status unknown);

my $i   = -2;
my $x   = $#array - 1;
my $str = '';

while (1) {
    if ($i + 3 < $x) {
        $str .= $array[$i += 2] . '=' . $array[$i + 1] . '&';
    }
    else {
        $str .=
            $i + 3 == $x ? $array[-3] . '=' . $array[-2] . '&' . $arra
+y[-1]
          : $i + 2 == $x ? $array[-2] . '=' . $array[-1]
          :                $array[-1];
        last;
    }
}

print "$str\n";
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