SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '213fb900108915e03e131e10f9618041c43b89302837a9a5472dfc7f481cc3a0' 
  AND token = 'mDc5n7jSAUplxd/BkIyXLKMPSBLTCAT11CGPkZ8azgo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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