SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8fc0bb40943ad3c8fcb989f011975f6ca5a7b2a7ab659dda723e808712d0b297' 
  AND token = 'gHLUDUO/gRssRlyhggD0DbGZtzFwSwwP9Dec56eh1jM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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