SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '52d085eb8ef3444333065555cd74d3766eb5a989968a5b30807abf347cb1a114' 
  AND token = 'sySYCXKS8sTF2e2//0YJ6MaiKAHOeEzK9tfhquS4BJU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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