SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '31f36ccb9d7df85c4a3d883797c6f22c5dd5108f7cba5b6779b3345691089253' 
  AND token = '9HUKIHLqej6Vf180qsbMhQlYhz9AFujXkiEShqMYOAo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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