SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '312d4e53f57b1728b1a21c28e0050b9b2821f3771387fd6ddec0aa7400bb5f40' 
  AND token = '4mQKhHsVt0clretbFN+8CMPBTZIjoljULpJ27LYT9Ys=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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