SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2840460fc38644c3872894578acc097a098324a44d612b824ab11f318ad12590' 
  AND token = 'QINCt7QXI8tGkDxYqCf5Zag3Lgg6yXGkq/5IcPUZ694=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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