SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '481388cb3c0372cdd351ca88d19f55561d9f91bcbf5f1df34bf10bfb43a48824' 
  AND token = '/mhtR/4FrZpqDaIFDUzrHk0ihV1SLUNUJ71BC7vGEf4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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