SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'db63ab4fe04b12ab116debb22624abaa84d7a9a861275fd9da904ec8b62abc84' 
  AND token = 'z/EMzTsxCPpj+EkFSAzpdmgxpMaY9gZdRLrP5Lvncb8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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