SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a765f39c2ce5871e583620b677fdc7efd79e20bd857e0a80e8942c7d4207e7d3' 
  AND token = 'UaUqblEUi//IVpePkLgQJWH6K5rDFh+vmEwGP1ow6h0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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