SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6d634d289e95febfe36b4dd2627d6a89b58aba97dc33fee171c3d9bf180236b8' 
  AND token = '7EeA3OvgEJ6RWyQXWcshAWteVMrx/gnkgFvQlg8RKAA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00058

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}