SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9e2b53b85cbfb4977e6a989bebdf66349c83cb1a3a9491fda744a14e5d77e465' 
  AND token = '6Ytg/ZDKl4HnKB0bZIHkyWAvhTdIyx+Ejzn5ml+7GhU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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