SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '77e5a957f2bf5f929f8e20ed3834a108dc0624fca8cf425f287ece5e33ff6780' 
  AND token = '/7v+RCA7vLFMybdzan19n2QrGXh7xgzvvO9IEv3Snn4=' 
  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"
    }
  }
}