What is limiting MySQL to write max. 10 Inserts per second?
So this is my SOLUTION. Imported my data of 500.000 rows in 3 minutes. In fact a lot of this settings is not for company grade systems. In a private LAN with 1-2 workstations it should be okay.

Here is my config file for the record. May it help somebody and my future me. =)

[mysqld]
pid-file        = /var/run/mysqld/mysqld.pid
socket          = /var/run/mysqld/mysqld.sock
datadir         = /raiddrive/mysql
log-error       = /raiddrive/mysql/error.log
bind-address    = 192.168.2.104
port            = 3306
#hardcore performance https://dba.stackexchange.com/questions/29913/innodb-insertion-faster
skip-log-bin
skip-innodb-doublewrite
transaction-isolation = READ-COMMITTED
innodb_flush_log_at_trx_commit = 0
#if you lost root password
#init-file      = /raiddrive/mysql/setroot.sql
secure_file_priv= ""
innodb_read_io_threads=64
innodb_write_io_threads=64
innodb_io_capacity=2000
innodb_buffer_pool_instances=4
innodb_buffer_pool_size=8388608000