SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '006a4f2ffa4bc09f270a67b911c557cd5bc822bc708a96d289559053e06fb286' 
  AND token = '2cVVt6r+imTYdj3kqaoErtddKZuYUVtL6bIZlW0oKRY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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