SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '39794c76b701b33a2e94278dff8aaa06528e1f92576b58682bba2bb67f951576' 
  AND token = 'jc6sn7BQ3/6YldT9ytgGn2dd2x3KaU8uQYyZM5Ly2Vk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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