SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '38882a4708c162983e95e4ceec976ab31e8fd3eb8db065205af617ed264b3f30' 
  AND token = 'EG7azVcJNyg/ezhoBUhdlbn31AZZ6K5Quk0r+RZNs68=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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