SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b6085ac2da9e6fd1dc3b504ee2ee02ef240ca107b578d7ecba039c75a74cb2e6' 
  AND token = 'xRV8Bzhkru4/V5+tYuJeQnWxylUQ+WG9jgzv20LRIdw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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