SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '841dcdf0b29ca7995f1f532dba788a24b90bd0ce4ca2bedb346dd37cf53ff6f1' 
  AND token = 'dCHQc0kKOfkr3cWf+fJk6sIBY/+HChcyigDB3BwIYpI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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