SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '37b3400c079ad6fbef1476c4d615118dbf5cad39a1014a7a1d4038026efaeae8' 
  AND token = 'Od4qFMUzMCTDlMQeVOe5EjOSY1v4fNxjtLINMKUpo8I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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