SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0a60a897caae47f9a015cac19bcb124ff3ec767f010109a5fbc369657332b659' 
  AND token = 'vaE2mxwdrCaGMrXktuw6+IUWHEjwSOXiZJIpnrPbSOo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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