ezNCrypt looks like it might be useful, promises TDE for MySql
You may also consider using MS SQL 2008 to store map data, then take a look at Extensible Key Management . There are several EKM providers, such as Thales . Using a third-party EKM would be easy (perhaps zero development time), but very expensive (I think $ 50,000). With the EKM module you can use Transparent Data Encryption
If you only need key management, without transparent data encryption, StrongKey is probably your best price / performance option. You need to spend some development time to integrate with it.
If you want to spend time and develop your own solution, I can offer some help in the answer here
Good luck