SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '26c278d68424f0e357f8b544e9ca8b4bb25cbdff9d9f140dbce328d142a5da7b' 
  AND token = 'Ol8RUiBjFpxVH/3+DNnvFunWrzrMXcZVe2xwPt4gaak=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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