SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b82c207e72a84637c83c11f63b422b0b7aee91fd70d91a48f203404fa6db6cb4' 
  AND token = 'l67b4MgRmBDPXcfHFiP+4kyLU+UBYHrJhuBbqAhFeIA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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