You can do something like the following one-liner (which I've split into multiple lines for readability).

$ perl -wE '
    use strict;
    my %float_urls = (0.1 => q{A}, 0.2 => q{B}, 0.5 => q{E});
    my @wanted_urls = map { $float_urls{$_} } grep { $_ > 0.4 } keys %
+float_urls;
    say join qq{\n}, @wanted_urls;
'
E
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