Unable to find the screws for the TV stand.
IMPORTANT: This article applies to the KDL-xxW590B series TVs.
The screws to connect the base stand to the TV are included in the accessories box with the stand.  Go to Parts and Accessories.
The image below is an example of the accessories box.
As shown in the image below, the black screws are in a small plastic bag that is attached to the bag that holds the supplied stand.