SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e2fcfb9164110b327030bb82a3dc475410a28b215d830cebe1c39e4d9ef256e1' 
  AND token = 'ylbjRHp0AmvF4CqHOxpiwF6qGjrzYf9NK9/Braz/GSU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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