SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c2ccca5c985e23511a9a3f611a2c54513caf8e8b28d5b66e6bc7b07414cb7f2e' 
  AND token = 'QsyMyI1MgKbOiXrYh7wBLz+osds+O9hUuHE+T9qg4/k=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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