SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9835b3b54b8589b9931af230077226738946b363a240d77990e05a1e35a6a900' 
  AND token = 'vAd4+IJOHcyqu6hf8zZz9PWjcOM2iEI8AlRUFFi39AE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00013

JSON explain

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