SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '68b6ccb6cc76dd46bcae3a325f81c54ac6d928115eb47b87d9078bd0232ae654' 
  AND token = 'McmIoGbq8hG50Nl+prZOqaUmlUB7sirvNYYB2QYMyAc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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