SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6d7ac75ec7a2e5501b3c21135b86d6dfac04f54d6908d4def95b012e9eb23be1' 
  AND token = 'urvik8lJCs+C2GxjVjKDiU3bvFWPnqkO1KD1PnKSwnw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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