SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '09c0f3e321381b06907d78608176d763a63fbab8f020f6208231b063cc804237' 
  AND token = 'UiCKPcBpmGgXdCyIptUwJMfqobsuZZ4iFctE5sbyEwg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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