SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '451748ee548e2a4cee00ff4ac5a6c87a7ce6ed8737b11238cc4a337d03577369' 
  AND token = 'SrFamAnMTjduwa74UEJpJznqpCEQs7VQ2d8EuAHJPhM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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