SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f4734325a439369c4ba9233d964c48aaf71d921d8cd5b8b17579c5900c63e77d' 
  AND token = '4Kdi2QHoAXvC6vO/bg5f/yW6LGEH+2/WYJbd6ijZSsk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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