SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '386ad8dbb612b49a5b70cf8d898af5cfe83780cbfbc22d156e35d48a60b253ab' 
  AND token = '+QGzV74Jqz0hyNEL5PwVvPNzWiKu7IprlGTy0Bo7CMA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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