SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e91c30e360ca333821013fc5eee2616646bf85eb61ad8c12596702bd60bc5a98' 
  AND token = 'l3kbVleRcgO5iB8uscSMorIZfWd3Crc9A9nrPZzFa7s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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