SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e8cf9a537925b2ada08e1fc6c41d5b73884daceff8a9ea6736ee2ba7d519586b' 
  AND token = 'kmQDwMKm3HfyvAumSfyfgBb+Lj+0SwUp0AZU+HkbYEU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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