SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '29fa493dac37c54b81e0863f5a9588ea0957b9b062035f4df5c750987293efd0' 
  AND token = 'xyZ3oHYRLZ4TjBgsdhdKlrPcXHywa47tOV7BV0j6qRc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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