SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e517c419d39da2f0e08e35f6617643b8f672720449e6525d829e5a18bdb61aa1' 
  AND token = 'Z0rGDnjTOL9hWWqXGDwwW5zh0ErKgMXjIMl+yQ0TX/I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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