SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6d21eb94b2f0c6f102cfd3c2412fec6557435b81f8586861a63c9bcabc128f5b' 
  AND token = 'gVbWA9dJqMY1ldUMBMjSEx4dQZIxZgLm1Vg/vZ0lzgo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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