SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '551662613f01ae8b66d03d2827629c37234a4930ec3fd6ee8d33647e900ee19b' 
  AND token = 'ZDTt9Sg8+WHdOo5JSjhkv8PO+zYAnHr+OmGJPk6OCzI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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