SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a03478978dc9dfb6c6f1dacd6be608f94526e8a85ec164da52020fbfb89703bd' 
  AND token = 'ZlKcDV6tYKmGg251+kLGZZjtUKqF43U5ONK9LVNZvUg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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