SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ff6ef0b3fcdd2927e4c192f006551a3687472f9484a377b1e875ba244d6e9beb' 
  AND token = 'sg6LkgLYU5Y9nwU7jcZeQq3AuqsVdD54ZJBNrUKJfL4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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