SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a5dfbb10af7b905b850f8c7e44ee0c198a4d5c913bae04d5410c2ab680bb56e0' 
  AND token = 'qGm3MxsdoQfijtp9PwCLKy43Z5OTcPCA8sRdKpyOjvo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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