SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd9589a5f7b555a4e2989fb1f5c600db97970699e4deb6885407793875a95b754' 
  AND token = 'nZ4qigrMXj0+eOtwSRYFKunl3hMCh+zkmyLwBvirulo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00124

JSON explain

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