SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '427583fff4070b29270a71d1b4e3274e1266570a28d628d928b47772bf85066d' 
  AND token = 'n5Z7SdR/hOEtotm6FTU9i/LN/mh629ShL2VIkns7rvU=' 
  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"
    }
  }
}