SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'df8fd678734b5289022d93153c6861f54acd241cd8767d77edb826ca1fb4a296' 
  AND token = 'HAltIExfFYOApg/tpXYmfoQd4HKBBuFk62BvJCiToYg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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