SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '8d9e4cfc938d748a79989ef1892c0990571f21c3e554e1faa3d871a6359fea5f' 
  AND token = '4MbhC77IeZqQlypbwnBJWvYyJuryAAlK7L+QUrkUpbg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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