SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'feed7dd12a34e042e89dfa06a6dff5c1cc4f0e59efd28bd7eda6aafc2ce50e91' 
  AND token = 'E6DT6nABeu3kek8R6lwNfKem9JlRvBAxMtfPcy5sZqk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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