SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b92cce2412f6cd677373cff5af1968c9e210b16c93e9a2b84981aae08d234e92' 
  AND token = '++KgVjQ/3+zDsk6D8onF5q47QE9tCOJBxq804bCvoBA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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