SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '916bc6680cf1e85a3af5ef09997ee1a78c509998bd0916b70ab199b1cab6a323' 
  AND token = 'eWiSN8cDRkcKggju7WNXWsIaI4Kbz6sf/b5elEBL584=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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