SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '912538590daf7676340cb73d93f5c08a25dea270c98a9b9455c1f417914ce1b5' 
  AND token = 'vqvMmLNVR8zIY9RrQbN+WdR7jUF86QYNO/VOrI24vj4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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