Unable to retrieve users using v2 API

Unable to retrieve users from /api/2.0/search?q=SELECT * FROM users endpoint though it's returning 200 response. What could be the reason?

Here is the response:

{
    "status": "success",
    "message": "",
    "http_code": 200,
    "data": {
        "type": "users",
        "list_item_type": "user",
        "size": 0,
        "items": []
    },
    "metadata": {}
}