SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fc8d2028e9e9bf232cff624e115e3d6347dcd2d82393e124763a4bbad8df7341' 
  AND token = 'MB+UrRSSeUcWnB84F69sculUjLn6qwou5UV7W0KOUa4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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