SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b4475c3f5d820fa94f26cf1c8c6239f0192ab3da9af63382fba7a48a021923ea' 
  AND token = 'Dy9m7jJsZyIgN6Hm8MvXfY8zJ0AUiq2XFGFvGlrJqkA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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