SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '39206a589671bc38f712d058d0bef2711f6150394ca66925ce61aad47f4ab55b' 
  AND token = 'CVfxzwZKvxojk6KPn2ZFi5MkYAj9gUMPNkK9QC0ro40=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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