SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8a14332c3214b9fe330c3a14dfdc0e1413d6e42afaaa359d9b81ba799f00def0' 
  AND token = '/IdUpVPJFb23NvcWrF6LQPcnSg+jHZYijMzukqlw7iQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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