SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7e231c3bf2dc48581b416d78957d84d678482b9ca623ec43550ae0afd2ea3702' 
  AND token = 'L/XO3iOg9qe3FdoGkQo/LFo61fOOegJgsePYBJuxd1Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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