SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5f88d3bb1c067c04cc0bb1f2651533044ef2a35475b5b06c6ed165910be502e8' 
  AND token = 'VCucTh0jsvfqHOyNYHzR4/hy+OZIhYLSBJ/I309vtlw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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