SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '937445e879c64cb29f91053940636ebec5da0633db0e3b56cf6e2666de718743' 
  AND token = 't66aiFdxfVmXUEacTmrXtytUdOjT+kJ7g+B0TVnFlTs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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