SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f784345ad64c9e575a8bcdd452c023ebe56d24d384114c54fbe03d587ccc03fa' 
  AND token = 'UBHERFZbAG59IDfMgAdyqyeMncvvyTAdmTq+Zk8VrNw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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