SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6f4cfcfed10e561f399e863b4cbcfe31f054699bda3451aaa21f875931023c83' 
  AND token = 'Qu6dLteH1mft6ZGu+501upG/Eh9/jwFvr6KeJ7rzgug=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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