SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e9fab26f8a6a72708c697891f535ce278819d0bb2e85f4c04fe175018483949a' 
  AND token = 'RNkWATHtlj2xqcaAEpYAamwH1xRrO43LcnC9uKMNyio=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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