SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9e56d251d7c15c789969c65be1ffbad189617ec0a2f44b64e493d4ba88bd60a8' 
  AND token = '35vpV/0tkVL5ZGQj5y9ugWymogNmCvN3NtmZu7IKDgU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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