SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2a4256b176dfe200d58457035a4463fe582a610570bc6981d6246b4dc8c74784' 
  AND token = 'DplmQE/EtFk87sd7XVGJoO1eHXYw8qP6xs8t84BAk9o=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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