SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '37cbfff7036abb0e9670cdc2e1e1ee386af58dad3142f11d267a6c12399d06fc' 
  AND token = 'j+Dj4UhCf4qrxFgfyLFvoFFfSw4w3syjw4BPBgMdz7w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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