SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '82c69a75f181be9d44afc3145af6e8be43c9bc38816236543540c56987a57c9e' 
  AND token = 'IRAHLZGVGGUuNuOdAo4LY4C49jFwYIu+bK5zueFTcrM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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