SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b7f1917a0099dec3c8140e1f5ae75310a9223369c2592b65bc78c6582f13fdae' 
  AND token = 'rXMnzR8PPpIXUtBWXVkrDtsBMPcPrTO46jRPKhWgIJo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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