SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5a8a7ff445043d1e846683059d3002009d2ccd055e9afc4a5cecfde66b4d775f' 
  AND token = 'mLIrx5VqKgwJ9OsHEjrcCOh0nCRjuU1OJ4/YinezWGU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00047

JSON explain

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