SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '87998ab50e0b45aaebf720763e7c84af3a72514a4bf836a9434284256ec921c7' 
  AND token = 'jQL/NjlOC9w52TGZc99LtSBhj+gIO3VBk+cYJ0PLk5o=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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