SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5e08ee652ab4081493e5c4f4ff9fb1874ebf938bd3db9241f5586df47ca9fccc' 
  AND token = 'WB6svKPb8KAKrjQvRrwn5iM8tEij+gVkphHQucDLYv4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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