SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b6bffa2ba32a44e84f1246c26e4b6f0ef247b3db4886fbec266176681c160197' 
  AND token = 'KtKiSfmEV4I6qP+/gUzaTNXmvL1BqqLDHiwr0Xm06Hc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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