SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '79a8ba6a823eb46d6d42c50662da6fbab49f73ab0d435a8dfaf41c8be8ae6d7a' 
  AND token = 'HDDIZrWktVMKLBuZsH+kad3n6QNqU5MHLzYQuIhNwW4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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