SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '596590858b5a36898c3344fd3340fd6895e13f64f9a0866b6138814305515a27' 
  AND token = '/llGOKzZfCIRZh7heLynDkv4+osDUXPFHeDcSafrbz4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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