SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '75ca0e2ecbca33f1299749add8886448796505e8864dab99ddc9860754013e19' 
  AND token = 'vRX/B5OGwGcOWxXzAn55YyhMqkb2dYnn8yipNmgAzTY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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