SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f4df7c3ea1e5ea9a995c04a377248e791cf6a1d5e851f786157e87fb7daaec57' 
  AND token = '1f7gLClZUZM7g8xwDIjix3yW4uwHTM5Y9uPVIkBAQ/g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00040

JSON explain

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