SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '94c3700817a0f03a354c55460b746c528b6da74c20c714c5ec1eb3e95991a591' 
  AND token = 'aJw9UM9gUZrph+NJ3jzkwVkDxdxUHIPfC8L8wjik51o=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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