SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a6197bd7be5e0da9e6e0da347273238d42eae3011c750f17d1de822e9ea1d719' 
  AND token = '3dGzVFQZq/CQA20jWCkgH18dJPDOG2O+wk1cijzN6gs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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