SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '52c2c63a4b76c81c82065159f2f66d7ef359ba09044c58a622519ecd045afa1d' 
  AND token = 'scQsCB/IH6AthgvZTQ/B11EgVlJKabXDlffbONrfPyI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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