You could take advantage of the super Regexp::Common

use Regexp::Common;

my $re = qr/
    ( \w+ | $RE{quoted} )
    \s+ => \s+
    ( \w+ | $RE{quoted} )
    ,?
/x;

/$re/ and print "$1: $2\n" while <DATA>;

__DATA__
key => 44,
"key" => "fun. \"yes\" 'fun'",
'key' => 'yahoo\' "fun"'
[download]

Although this leaves the quotes around both keys and values, which may or may not be desirable, and won't work for anything more complicated than simple constants. So as zigdon has mentioned a simple split should suffice.
HTH

_________
broquaint