SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '21894e2c54fc07d93bbb2610b7f4bc818859f9f410d3d0cd6da571e34b2672d9' 
  AND token = 'BOxHEnBhoXEJizWdW4mzXuqJxTrkfPnjIbtY7r5yXNA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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