SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6ae6681906c09488e23312481697092b6c57e94b1e81d31b34807dc835f2b9ab' 
  AND token = 'kf1g2QkWJzRF/tZnDp9ONVOiB0I6XX9GYyOBBhja5jw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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