Why does this SQL-Statement lead to an error?

I am getting quite angry with this, so I seek help from the crowd ;)

What I want to do: We have a Unity learning game which shall implement a login window. The entered credentials are then hashed (the pw is) and sent to the server, who then should check this against a database.

I have the following table:

xy.users_confirms with the following colums:

id username email password hashcode created

Why does my code

String sql = "SELECT " + "xy.users_confirms.password as pwhash, "
                        +"FROM xy.users_confirms "  +"WHERE xy.users_confirms.username = " +"\"userNameToGetHashFor\"";

lead me to the SQLException "Parameter index out of range (1 > number of parameters, which is 0)"

?

Thanks, any input is much appreciated!