SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3df0d21875e291a1637ddb3b8febc0c5408a3cf1956605b6d0883807fbe9562c' 
  AND token = 'ojMA39JlXgnEcoe0ZOwodHQjrcy3+rdZZtOET6xLJFg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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