SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1a747fe916dfb449000ba3c505c11a25549995288152ddce1d436a33de42c620' 
  AND token = '+qAtMWOydASNj17SuLNQ6BSMeLCqWgLK0ltTE72QkZ4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00052

JSON explain

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