SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a3b9cdfd3beb5a399feaae9477f5761ec392225fe51a5f2480164af0d165a185' 
  AND token = '2yfKPm4A0NB9pKvp2spaHZgGZecx6jiKEs1Fk2da+H4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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