SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2a71945111cabfa178a9e4fee90b4e9bd329016feef6a6b471094007033d9dee' 
  AND token = 'aOUzC48bwO4VY0mqs3ZRLrrIFDElFtPO1zSNbJBKVjU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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