SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '384b37cd5b072a2521ec3d3784cb7f7fcdc87f5e1908e0d2a208d4f26582c0c0' 
  AND token = 'YLcfTFbgCUz6+dP3uVvVfoMShWOAghpBsUFNWEKsjuQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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