SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f4265cae84649ae6c299f1c0e9250184ae5a0f183fdad70a8d0543db7f858909' 
  AND token = 'KnP//ZrinmoCeAlsopPtWPffJ0bs/Kx3l3AQ3XhAS50=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}