SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9b4c2a94257b426594e4942ed67fd2058bd34e3badc956cc85e1da88c81f8055' 
  AND token = 'X8uD3qXuxLHLI4Fj/4BrHDEPS8QvnEVfpb1jTv36Wlg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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