SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8b439c035717802badb9502b0b66205e9797aa5627317607cc986bf52662fbae' 
  AND token = 'FKKrBjrpUQI9TW4PYhC4myIr4L9GcO/TxBhedpklGZI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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