SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b8e2db881f8e934e664badb04a30223c0c8902ea97127f963dd2115e2793b7ee' 
  AND token = '9ZpHqUVX3MeiJ7k8RDdvF3DIjUDZO9pHwDDygLzICrA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00046

JSON explain

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