SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2ed390430245fd46f893e36d294f07454d42eeb416c8b7a67ed15098391d615a' 
  AND token = '+ZSp/NtGOywB804m9S/TOqAE5hLIwn3iHriot1ybqrY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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