SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7f359df6f171a9b547775790183a3f8d5676e01678b43d67f4b38c64c8f5cf23' 
  AND token = '9+vvkCc2p3xeVJgjfRg1WpQ+BgEwTAGxd7FKTRBHiP8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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