SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3ece76cdc15906a9aa0639b707f99d142e0250c59a95a32c96d246eb19d7ab95' 
  AND token = 'a+ldVjAdUWxeLArk7JzTCckFgerlP4vC9GxOUEWuP6Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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