SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9593026b409965679cfa93f618afb571bb9a38b8c2ae350ae6d9e01010bf56ab' 
  AND token = '2RwSYT7frUZv+w80o9MqXeiwQYtwDuEGxWsy3bssaM8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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