This filled state of the checkbox means that it will search for both values '0' and '1'.
You can set the default value to '0' or '1' (S-056136 in the KB):
...Search cards will behave a bit different from "normal" file data cards in regards to default values. It is possible to define which default values a search card has to show by adding them in the "default values" dialog found in the bottom of the properties pane when editing a search card in the card editor. Read about it in the administration help, chapter Data cards, card editor controls toolbar, card properties, "Search card".
For checkboxes, add default value of 1 for checked and 0 for unchecked....
You can set the default value here:
You have to restart Search.exe to see the result.