SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '90688ab22cf54841d492cdc71248432e90e0835482793202c6f28da64ac35937' 
  AND token = 'YbreWLyJX5ZwcsepjkYNw4SJ5mhfU5HMXrx2hlUn+PQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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