SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '77ebb33433b75796c86a4466b061f78261f75c7925e7e6d3480d995740ed1491' 
  AND token = 'QqdzcTJ8/UnDxdoIDd0lkHrIVdsad5lMvXESK3wjuwo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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