SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3d151c76b9852b33100d6bfc0d64fd619db2725302ad24fbf6947aad3a54668f' 
  AND token = '36XcJaLnbK4+wpve1ekS71YhjgOnHlgBuRuIDWsSINg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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