SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e6f8bfd95be5c8377cb5cc8cd706d08dbfe35e4211cc0fe3fbc00fa4f398e5fe' 
  AND token = '6/z8xjuioIZw7kzwgRYfwaL1sVw//ROcNHtOcZXxrC0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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