SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3335a10a3c85ced0303920e22b8ea4a97158dd2c6537c14daf9afda0d7ac0d3d' 
  AND token = 'wjm5KHPhNm0xcMx91aWFT+YoFWsS1h35nvMSsGrmqIM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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