What connection string for GCP (Google Cloud Platform) when using asp.net REST API on CGP Database (API is on GCP)?

Question

I have created a REST API that tries to connect to a database and execute a SELECT statement, nothing more. If successful the return String should be OK otherwise it should return FAIL with some exception details (set within the catch).

Server = "google IP",
Port = 3306,
UserID = "username",
Password = "Your Password",
Database = "database"

It should't be necessary to open up for some IP because the API is on Google App Engine

MySqlConnection connection = new MySqlConnection(connection.connectionstring);
try
{
    String query = "select * from tablename";
    MySqlCommand command = new MySqlCommand(query, connection);
    connection.Open();
    command.ExecuteNonQuery();

    value = "OK";

    connection.Close();
}
catch (Exception ex)
{
    value = "FAIL" + ex.Message + ex.Source + ex.InnerException + ex.Data;
}
finally
{
    connection.Close();
}

i have tryed nugget: MySql.Data Mysqlconnector

The error outcome i get it this:

Connect Timeout expired.MySqlConnectorSystem.ObjectDisposedException: Safe handle has been closed
   at System.Runtime.InteropServices.SafeHandle.DangerousAddRef(Boolean& success)
   at System.StubHelpers.StubHelpers.SafeHandleAddRef(SafeHandle pHandle, Boolean& success)
   at Interop.Sys.TryChangeSocketEventRegistration(IntPtr port, SafeHandle socket, SocketEvents currentEvents, SocketEvents newEvents, IntPtr data)
   at System.Net.Sockets.SocketAsyncContext.Register()
   at System.Net.Sockets.SocketAsyncContext.OperationQueue`1.StartAsyncOperation(SocketAsyncContext context, TOperation operation, Int32 observedSequenceNumber)
   at System.Net.Sockets.SocketAsyncContext.PerformSyncOperation[TOperation](OperationQueue`1& queue, TOperation operation, Int32 timeout, Int32 observedSequenceNumber)
   at System.Net.Sockets.SocketAsyncContext.Connect(Byte[] socketAddress, Int32 socketAddressLen)
   at System.Net.Sockets.SocketPal.Connect(SafeCloseSocket handle, Byte[] socketAddress, Int32 socketAddressLen)
   at System.Net.Sockets.Socket.DoConnect(EndPoint endPointSnapshot, SocketAddress socketAddress)
   at System.Net.Sockets.Socket.Connect(EndPoint remoteEP)
   at System.Net.Sockets.TcpClient.Connect(IPEndPoint remoteEP)
   at System.Net.Sockets.TcpClient.Connect(IPAddress address, Int32 port)
   at MySqlConnector.Core.ServerSession.OpenTcpSocketAsync(ConnectionSettings cs, ILoadBalancer loadBalancer, IOBehavior ioBehavior, CancellationToken cancellationToken) in C:\projects\mysqlconnector\src\MySqlConnector\Core\ServerSession.cs:line 775System.Collections.ListDictionaryInternal