SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7dd52a344397efcf533e3bd17475d79924dd4a39e833e92428f820f7cac138e9' 
  AND token = '8SOra5eS+HPxu9cCnqDWlHM8y0uMvv1oPeo9Lyp0Nnw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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