SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '903f79937676ede45df4f151bcacf1917cb4af50997b106db3f3d1846ef46c88' 
  AND token = '2/57cghVh2glU+D9FikdXlzlpMVsabRufveVvFcbmQ4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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