SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '678961037e9f144724a9816332a47bba69e8011a08b7e7dad18c2edf9265fd0c' 
  AND token = 'HQwE8V5MfIMVtRzkrDxVeKAZZ8hZ9bkZdobeUQP3l6o=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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