SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8b453f8b39c26b91dc8ed90037bfe8456ca569be2e7c4d074bfb5f510a6c929a' 
  AND token = 'CzsXHdYqVTfd79044oTYY8hnMMAUzB7wXRXLCHJm68U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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