SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '267a67c48c714c71cd1f738396f418e2aba1b4968cad954470e266013c307d45' 
  AND token = '5pqg+UDLN5O4bjHZsHEARHqzF9nnwp6fhsyGsj6zpX0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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