SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'eb407bca6af25fec3eee242339511621896c2792c796d7fdc5a39bfe568f92db' 
  AND token = 'XfEamJG1xWPlpwC1lBmGzV1YWY1RVTgqad9QAfPFPFA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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