SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9904812f68d7a5a21bce3b7fe10f9b8ca3e6d45bad97f35281eeb008b020bf48' 
  AND token = '7XrMTf+XurJ/qjCNCpGyZWzxBhPLdoM3EyogmIMS7HU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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