SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fc4b5a9f28ebdb16e562f1a44ef98c8fd96cfc6d4415dd7b5987835cc5be1000' 
  AND token = 'Hhry6/2Ecw3Ol9rhvAH28gUqLu9meJoSzP+Jm/Cvb8E=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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