SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'af26b1997ae2e5d1d4212a05270cab5c950320dd38647a69bbe48645b977b1fc' 
  AND token = 'Yf+XlFTLxYZD9IcwYCOv2+LNIBoNqteCcUM02gB0Xe0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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