SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3ddc879b5ff424bba95ef5afe64bc56382c697f8f436f1f3983ab1ceb3514270' 
  AND token = 'k6JQXjgFTS6HZkv3ZMnfwABNz3GXgynK8VaPEbpFuts=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00051

JSON explain

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