SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '766a401f4974b0a7b50e3e78e732f990094dd9f49d0348c84d056af498b55714' 
  AND token = 'nnMOUXAvbchwlqRBrNqOB2uMxntqvmMyEtD7gpQZNLo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00047

JSON explain

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