SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '342aab8d4e9c89a88db33d781885bb2b53174bb092a13ee87efc8e1c1673a9ed' 
  AND token = 'q9xHCB9F4h9vKK1rCfqhRT/+IjYzyY4HncBVPbgY3LI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00082

JSON explain

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