SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '340647eb9b84533ace6759328c42b15917fdd17c3709c5e0d1a5ac1f31531cb4' 
  AND token = 'PfBbJq8s+OMqvwlPdndp7WqXJyT/9j0z+UH3kGa2hoQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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