SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8af10bc7c70bd949f934a4ddbf39843b1e53a39398b21405544a300d4516d9f7' 
  AND token = 'a1/rgTDQq3AIbq6zFVhXHMH+59v7Xsp+lJFrPFxoFhQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}