SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '91238344a7860a0f5e5f331b821c205f03735cdb654b519e1b7b73ed6dc5c969' 
  AND token = 'hZRSO21DwLuNqX+fFInuSFEFVapspmFCsyviTKbF9Yo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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