SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '81b0d0baec5ebbfe236bbda35fa2ef43b316cc68a3cbd3552e6a2a34855a5ce2' 
  AND token = 'wUFrmT3zz7X16+5ZSNlA72rTd+ClPamZGa5B/CGVgWs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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