SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'ba02259988087d777c5413cd37f44e035ececd138558f2052d369209106eb5f1' 
  AND token = 'P4GbyKqDupai8NF96IK6lCS6JH7sVweKMJEXf/N3MqA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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