SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a5e6f2de205bbb7d5ee3294b6543d5a664f8a7b22ee5ca5765dfd8e18a1e881f' 
  AND token = '8QbDXwYvqkN53YQSArFxRwzfHCxOt8gZzRyXBvyLheM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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