SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f95ab647402026555d9298f250faa606a783afc34d3f03b5d911caa6fa8760f6' 
  AND token = 'rnHrEHdizH14rhA90TamAYWWCGaeQudmAiK2mRrXqdU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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