open(OUT1, ">> resultsfile.csv")||die("Failed to open resultsfile.csv: $!\n");
open(IR, "< file1.csv")|| die("failed to open file1");
open(BS, "< file2.csv")||die ("failed to open file2");

while (defined ($line=<IR>)) {
    chomp $line;
    ($username, $firstname, $lastname, $lastlogin, $tokenexpiration) = split(",", $line);

    while (defined ($line2=<BS>)) {
        if ($line2 =~ /$lastname/ && $line2 =~ /$firstname/) {
            ($bs, undef) = split(",", $line2, 2); 
            print OUT1 "$bs $username,$firstname,$lastname,$lastlogin,$tokenexpiration\n";
last; # go to next name in outer loop.

        }   
    }   
}