SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cbd2168b48d18718a450cb5103a457e7435711a80c17e82449b3ad8c6b6d8881' 
  AND token = 'A++OSMp2/FdM2AienQBqczB3ta4knDJXvXEKsQ4+Bpw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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