SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b6bde77639137a3b6073cc425aeb9adeb53e85c8084462e33e8995a2399a4697' 
  AND token = 'nNaTmmgZWgT8nsRUD33emHNhl84GDerbAS7PCOzJzHs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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