SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1b698a8fbaf26f53940646fa5066c867ab6114cb84e471a060cdd1f46827be15' 
  AND token = 'tWFQzBWr+u/vMyFBWQAzPueWIdnRzVLyM3/e0Wak3ug=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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