SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c55747b1dc1c151f3b2abbc1731ebd2e38ac5c37c8943c3b91fffc9832af686a' 
  AND token = '4WSQw5AOFlXb9Y0RVp99QGolFzzwwamthtzeRd5M2OA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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