SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '254f63b3ccea7110454e9220b19edcde5851d2c506f7dd6d4226d442226f880f' 
  AND token = 'fBtWntukom/P4qUn3ywsiQMlVydLf6fFE44EHQVoSmw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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