SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '981534383479642471a948f0e606b4a394be09e94387af99b32a16390c2672db' 
  AND token = 'PePBQ7UqQKxQfXqjVDOCjSk6BTmbXUh26ZQLBS58naA=' 
  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"
    }
  }
}