SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '187f323c44e32222f543cc8eaf98a340eb5735bb046ee942446f8de4bc6321b6' 
  AND token = 'zuedZ17V6RvMCIBxv/u6NQj0kMstdOTRRVPisGBGq9Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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