SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '71f3318c295a9f3904d39414b4ae761da10261217dfd1678cf8c88e5cc4e0524' 
  AND token = 'ZG31MlDkx/SvwNnEexOs+YsOe9RzbKfijRzLaZvAGt0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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