Unless you are only going to do this lookup once per script, you'd be better reading the file once and setting up a hash:

#! perl -slw
use strict;
use Data::Dump qw[ pp ];

my %db;
while( <DATA> ) {
    chomp;
    my( $user, $pass, $db, $server ) = split ':', $_;
    $db{ $user }{ $db } = [ $pass, $server ];
}
sub getPass {
    my( $user, $db ) = @_;
    return @{ $db{ $user }{ $db } };
}


my( $pass, $server ) = getPass( 'fred', 'rocks' );
print "User:fred db:rocks server:$server pas:$pass";

=comment
C:\test>junk53
User:fred db:rocks server:quarry pas:derf
=cut

__DATA__
fred:derf:rocks:quarry
barney:yenreb:rocks:quarry
wilma:amliw:shopping:mall
betty:ytteb:shopping:mall
fred:derf:bowling:alley
barney:yenreb:bowling:mall
wilma:amliw:hair:saloon
betty:ytteb:hair:saloon
[download]