SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ad786c0be06a89680bc1630bfa9bec00ec712b6506bdfdec24698e850bee70f5' 
  AND token = '063iWx+KTin3f5fDFqrJtWDWaHi5ji6BK91tJtOeC7o=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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