Hashes are much better if you're going to be doing more than one or two searches, but here you are:

use strict;

my @array=("host1","user1","info1","host2","user2","info2");
my $host = "host2"; my $user = "user2";

for (my $i = 0; $i < $#array; $i += 3) {
    if ($array[$i] eq $host && $array[$i+1] eq $user) {
        print $array[$i+2]; last;
    }
}
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