SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '77ff0618bc20f3dc34dd5d0da56c411255013537ccfd4ed9ad7f999c4a60e702' 
  AND token = '4cr8jvyWfKZZRYZVWNLzQp3YUEBlmb4i7JFY0HQKFtk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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