SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '584a1a664c54081e52c322737122b8a8a52e477dd2e51fc49505f4817bab9494' 
  AND token = 'DV+Ivo7ci1EPg2ZOQHoxMfRAxwf/hvcjssjyfB/LuPU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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