SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '8cd840f336f7b2064e11bb48ade48032f4d9f75fc9e9c14ea1cb51e8fe7aad36' 
  AND token = 'vbKP6+vXJkr3gvTPYKZBeOrEzLjNHPWpKEDy2i5SRzg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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