SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '79ed72509d208c40cf9b27566215b2f97716e0ceaf78c2f1b3b533e0250cf7ec' 
  AND token = '5FXg1YjWR4Tz/4J1flyI76vfzdNdW+0+hhBZ8rpPPvs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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