SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '573e5706a37859da15c92f8c1fe922159619993e16f8a56b675dbcaf408ae52b' 
  AND token = 'YA+su8R8IZV5P1hFWX0JB6KMWe/zlgvFkowI+M2gPK0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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