SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c61cc79045c8b1a77fc6be4858e797f6aa0dd491441ac1206de4b7fd7c5d0e4a' 
  AND token = 'jCBjF35yGoGNyqjP7f6enw2mO+mhwuZvG8ULgxzSwtE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00012

JSON explain

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