SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2ebf6f40a70d2b63bda2fc16d94126d873448afa92f7101fcab91e19610d68fa' 
  AND token = 'QoG9/AU6UpNUDJNcPWlOqLqzXH6pInVML6tzqNMihG0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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