exists $ipsAll->{$key} will return 1 (true) if the key exists. If you need to get a list of the keys, umasuresh's answer is what you want. Also, be careful about using exists on nested hash references, since the -> operator will create intervening values.

my %hash = ('foo' => 'foo');
my $ref = \%hash;
print exists $ref->{'foo'};          #Prints 1 (true)
print exists $ref->{'bar'}->{'baz'}; #Prints nothing (false)
print exists $ref->{'bar'};          #Prints 1 (true)
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