# Option 1: use Params::Validate

# Option 2:
sub whatever {
    my @param_keys = qw/ key1 key2 key3 /;
    my %params = @_;

    $params{$_} //= undef for @param_keys;
    die "Invalid usage" if @param_keys != (keys %params);

    lock_keys %params;
    # ...
}

# Option 3:
sub whatever {
    my %expected_params = map +($_,1), qw/ key1 key2 key3 /;
    my %params = @_;

    for (keys %params) {
        die "whatever: Unexpected named parameter $_" unless exists $expected_params{$_};
    }

    lock_keys %params, keys %expected_params;
    # ...
}