SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7379ed16ce6bc47e2a44f059a209fedf84a475d71d1422cdc1d88a923617d9d2' 
  AND token = 'QgHBYWHe6j6A/WbDLk0tIqhUVXzCeYCsVBZPwtq3gSw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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