SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '85b7f216fee95751d9f89093327dfc3feccd501ac4607150376011af7ec981af' 
  AND token = 'aIA3HtlxTndhHwAEF660OwgnOdQu44ZuZIeK26+SG20=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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