SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0db4f1c8209d7afe26991b38b53bdaf2a33351516f25db26208c492a4a2abf36' 
  AND token = 'XKUlcuJQKRgu6NpJOBNg1voI1DzEOkLMtPBjufbHnug=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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