SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '2734b7217722a4cba9713b29dd3abe0b43b448f223660c684bef53b3790e5185' 
  AND token = 'ZQS8PSiDxrRN/kjp+qESH6DNzlV1RhxKZlSBQYKl1KU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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