SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd67104dc3d79985644b7d35d0e11c3fab4979a3fa9bf501202ef6c6ff2195107' 
  AND token = '+PS+slQthSze4wjIGav9F0kxMYHJLqhIFSvoYMWVvys=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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