SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '81da04338f81c5d3f095011cc1c740eec6cfdc13be66027972158202f303dbd7' 
  AND token = 'hN15Xre9pSoRmPMRaAnV2XgXTz+WW5IaKBSXFDlgz4I=' 
  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"
    }
  }
}