SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8dd49d45861666cf9c9330c8c1d2e0088d0be5392c830feef21b57b71b7f50f4' 
  AND token = 'SDf4xg/5D/K3ovwuKXjLEHFouYsL5nFszDh31Vs/qbE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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