SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '33a5f9b60ca648853820ca1147e271a3f305b4ee53c105c85e26c1f1a565fcc3' 
  AND token = 'jQheTxzARJ72ZFucBVrEpNYdNvZFffhkc2PHKE5WIfg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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