SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'db785fa5275933201d5124991957a3544d625625a015eff7fe54cba33c82c73e' 
  AND token = 'G3ggYa9xZeaWPge7lSTBxiXzNxGIiqk1PMuBXAJVGuA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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