roles and tokens are unique per user

db/migrate/20180208132723_unique_tokens_per_user.rb

@@ -0,0 +1,24 @@
+require 'carto/db/migration_helper'
+
+include Carto::Db::MigrationHelper
+
+migration(
+  Proc.new do
+    alter_table :api_keys do
+      drop_index :db_role
+      add_index [:user_id, :db_role], unique: true
+
+      drop_index :token
+      add_index [:user_id, :token], unique: true
+    end
+  end,
+  Proc.new do
+    alter_table :api_keys do
+      drop_index [:user_id, :db_role]
+      add_index :db_role, unique: true
+
+      drop_index [:user_id, :token]
+      add_index :token, unique: true
+    end
+  end
+)