SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '865a3c7afed489aa9284e3a63d67675adcb9d9eaaa6e883ee2978f1de82f8410' 
  AND token = 'SrF2yyqBwuz7t/enBwHkvykxLlqhZiPwd+oBSfqtObw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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