SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '88563bfee82bbbd7b88db64724d08edb26df7e0d5c8e3ccfa1c2367fa4de4cbd' 
  AND token = 'SlwJHVL+cpfvAe4mffy1QDBUKmJSdOhYjvoNVlXut0o=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00057

JSON explain

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