SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '15e4afd304b4da970afa6f1e245b49435b773ec66a3da3d92ebe06f16afc3227' 
  AND token = 'DUqfVGzIU3gcPNcPE/UdfzHQWgZeciiuvmGyeBkNiT8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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