SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c5aa8024ec88d725216f2c4026524ac4a6cfa81b39da244a05896d7470cbb76d' 
  AND token = 'rUTKn/CAfvzvMw8gob/+wpdUB/z6okzecvLUx/Ml7qc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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