SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'aa3dcf3d369057afcfe687f82850e6718217c522c9ff17e52ba614945b81d815' 
  AND token = 'oPeY4gv7XDhj7rvfzYQgMXmXQyNsBzE5NXkWccesfT8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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