SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd39e154ef00c169ffcc1fd8ecb7ca463caf853776c622ff0b867faa8cc62b2ad' 
  AND token = 'K7j39FbKaQz+H0H0LUJfS6jobMxGc+D6porJQuJ+m8s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}