SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b5c73ca58eda84657ac72118c4b7d760f059551525f443ad42e56cc9eae0bb1e' 
  AND token = 'MHaTHjRXQyDGD4jKITvsd+hMQyJafrgX932lalg0uK8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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