SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = 'df752456f29ab4837747f3ea376470166cb14a087e83c5edc11691b0ba65a3a4' 
  AND token = 'rKavLL73phuNKxb4kyI4QoBfdbrmiMWwEVU/UyxdvNQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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