SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '31d155470b5904443eed268d9720f993c34bae69f23d325271f83bde552ac4b0' 
  AND token = 'yp19bfdCs27TUULJ8JmUiKbaRhDn3SzsLEjGzT9IEcs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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