SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9f82d8253e0aa12f2502b1b14d5315d50d2bf1ed3788d25872dd128639ba3cfc' 
  AND token = 'QxdlPPVVHvXBunPL/rK3yo/GYzxAocO+wAFSTg+d9zc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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