SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2a789b02a28c9f3fa82eceb9682222ef21e1ec4d2af0059c329d91a8998133af' 
  AND token = '2qf5VzSlTjlFzqxaSUWsat9y5X1ayXq5jEtZU1D6jgI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00060

JSON explain

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