SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '181f7661cfdd992c72ddb15876bd963d0296e410106c63369b15741efad6e4c6' 
  AND token = 'm+D0pChRbP98UN1shxgAxYGCqxrDVxCEL3bJYK2MVXI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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