SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b2a6d727b3293c5a6b85b066dd0083194d49d2ab9ceab336e6ea38bda2c75cfa' 
  AND token = 'zHfwgYFolnlzFHrmxXOO6e7MrL6LtEHQzg4kCDGp6/U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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