SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '673af7cbe3fee27796cb25199ad9f5b124439170823dc8c027344a4b0330c4d7' 
  AND token = '6yCgrfnGIEXC07Upo4WkaxCuqNtVdVxsSr/rBJaVmnM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00051

JSON explain

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