SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '90976b88cabd2073ee5d5609dd20edf9e2b60bc76e98f1f2a2e757137791c39f' 
  AND token = 'VsRFzDZBIB/buVt1HcfIqkjGAdwUWtCXnPKVd/BE9D4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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