SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8b66cbd2296b91077952f32d9bfb1e7ef513678fb73b3d265683b0c74a985d59' 
  AND token = '5I7v/zk9QmlCQjVis7EmYbXiHZVKMwz6gQe7d5U+gyA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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