SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8ace5c178484b20e43eee939da9e68e0dc62c124a65c75ba29a4220961c2fc53' 
  AND token = 'd952kOettNH8w3g8mUoSgHJyiwiJmeinb052frYdCbY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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