Using multiple server databases
Yes, you can and should use multiple servers if you have a high load in your mysql.

you need to see what solution works to you:


Replication


Master -> Slave: 
In this one, you will write(and also will be able to read) in the master server, and read from slave, 
Master -> Master: In this one, you will be able to write and read in both servers (they will be action as master and slave), you need to be careful with AUTO_INCREMENTS 

Cluster: You can have a look on mysql cluster, I'll recommend this option if you have more than 4 server (masters or slaves in total).