SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0d299b478548c30acb7ddb5544e36e31af56de861a7f42f88588ccd8b9e9c310' 
  AND token = '3DdkcTxsQcs2RE7CSWFT8hCEXSiBiVykLoBcn8uRPh8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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