SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2e5bb23ff943b47644e2d52a559eaa43737d7df798b5f5120329403f440b6597' 
  AND token = 'p4MnucdKvjiAuK/OGs2WPzMvfQjYL4Xc8CwiIz65ZLg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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