db_query and condition in custom field
You cannot find any custom fields because fields created using the field API are not stored in the node table, but in a different table. In code, you should use the EntityFieldQuery class.

  $query = new EntityFieldQuery();
  $entities = $query-&gt;entityCondition('entity_type', 'node')
    -&gt;entityCondition('bundle', 'article')
    -&gt;propertyCondition('status', 1)
    -&gt;fieldCondition('field_event_date', 'value', '2016-07-29 16:25:00')
    -&gt;fieldOrderBy('field_event_date', 'value', 'ASC')
                    -&gt;execute();

  $nodes = node_load_multiple(array_keys($entities['node']));