SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '914d83c54a406184a4879fed559e028c7ac90ad3208be49e669767327f0f8b9b' 
  AND token = 'n+XJyh22qQdKx8eDRm6EV12e5n0cXdZAsskQoPIwJP0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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