SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '9540c768fa77965e37e095de382322eee6f314329e246041236b91e9bcb2f209' 
  AND token = 'kp1MQvGtQlfOWuSETrFNJT5rbbKkABQ+JaX9duY+SqU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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