SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f34cfd713fd6a3d0b9679bde8a572e3a266efadf1f4e2f4dea922290505c97ec' 
  AND token = 'rAvDk2BHiyN2F4QWzUIbBveXzjk+ks7zYSdXBgsTEeA=' 
  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"
    }
  }
}