Do not use Mysql, it is obsolete module and its own documentation recommends to use DBI. DBI has selectall_arrayref method which you can use to get all records from the table. If you want to be able to get phone and email by username you can store result into hash like this (not tested):

my $res = $dbh->selectall_arrayref("SELECT username, phone, email FROM
+ users");
my %users = map { $_->[0] => [ $_->[1], $_->[2] ] } @$res;
for (@usernames) {
    my ($phone, $email) = @{$users{$_}};
}
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