SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd21ae0ca072466b8b1234553473577ab94b9d1351525430f97f160794da6f44b' 
  AND token = 'Gxrd0PiUEzNyKgucqLKn83YtK7xBOpidb4f41pk73MI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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