SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3e3cbd7f508e86207fbf2d059d6ae8abd57b67e66d985040dd2c4ac12136f00f' 
  AND token = 'lmSgQHcPa5dw75fWMcGOzzOO5PjiEOryPIJQikWlGBc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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