SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '027bd28f12f712915b52c37a4a54989bbc849f792e0c7806d667af08810a7ca9' 
  AND token = 'N8frpIj3SQLOB1ipB/yAq8hnu3r7rYqrvCOzuS9kml0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}