Mysql database replication with geo-distributed servers
One solution that could work is a Galera cluster with one node in read-only mode. (See e.g. here for info about geo-distributed Galera cluster.) Galera cluster is a (virtually) synchronous multi-master solution. MariaDB and Percona provide this technology, as does Galera themselves. There is one problem: Since you would be writing to more than one node, there is a higher likelihood of experiencing deadlocks / certification failures, including on commit. (See this article for an explanation.) However, this is something your application could handle if you take care when developing it. 

Be sure to review the Galera cluster limitations before you decide on this technology. Some of the most notable requirements are: A Linux OS, it only supports the InnoDB storage engine, and all tables must have an explicit primary key.

MySQL Group Replication is a similar technology, but this wouldn't be suitable for geo-distributed database nodes as in your use-case.