SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5167f437927537a8b720bdf606a5156f5ea604723e7585cfc618e8a8fa6fd2e3' 
  AND token = 'L9Jq1lCcMem6KNwjb/7z7nhg4qwU3xMvL5Pg/DnqGu4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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