SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'df1c793299b605a342b4d1c8a7c48fe95a3c3ff907f11cf039f280fec8af2369' 
  AND token = 'I/0KRqentYwCPTE5Sj9FRB+f8S/BYGh/WSzbWpnJ344=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00054

JSON explain

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