SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2ff543997de7b669ecc15699d05c1886b861a4c09bd5283be3dda21014fee4fa' 
  AND token = 'XMkkO+WDETswAnSamp3lAdsYcPah79Q0buT0jKYqlvQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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