SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'bb96b6df9b8cd90060b9ef3c102d71724a2b8836648f35978517c31523d6aa51' 
  AND token = 'pwFzpM0BtKqx50cSZ9D47kJv+RYIGxOHla3e88UppGI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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